question

Keeping in mind that a normal distribution is a model for a continuous variable, which one of the following variables cannot possibly have a normal distribution?

answer

People's opinions about a new tax law (favor or oppose)

question

A card is drawn at random from a standard 52-card deck. The conditional probability that the card is a 2 given that a 2 or a 3 was drawn is

answer

50.0% (1/2)

question

Which statistic is not resistant to an outlier in the data?

answer

Mean

question

In hypothesis testing, a Type 1 error occurs when

answer

the null hypothesis is rejected when the null hypothesis is true.

question

The result of an Internet poll was reported as evidence that most people believe the pledge of allegiance is constitutional. The poll was conducted by posting a notice at a website and asking people to respond. The results were based on 235 people who responded. Of the 235 people, 172 (73%) believed that the pledge is constitutional, while 63 (27%) believed that the pledge is unconstitutional. The results of this poll

answer

cannot be generalized, because the results are based on a self-selected sample.

question

Suppose that a student needs to buy 6 books for her history course. The number of books that she will be able to find used is a binomial random variable X with n = 6 and p = 0.30. In other words, the probability that she will find any given book used is 0.30, and is independent from one book to the next. What is the expected number of used books she will find, E(X)?

answer

6*0.30

question

Suppose that a 95% confidence interval for the proportion of first-year students at a school who played in intramural sports is 35% plus or minus 5%. The 95% confidence interval for the proportion of students playing intramural sports is

answer

None of these choices. (35%, 95%, or 5%)

question

If a difference seen in sample results is "statistically significant" it means that

answer

the difference observed in the sample was unlikely to have occurred if there is no difference in the population.

question

Some statistical procedures move from population to sample; some move from sample to population. For the following procedure, determine the correct direction. Confidence intervals take information from the ___________ to the ____________.

answer

sample; population

question

An outlier is a data value that

answer

is not consistent with the bulk of the data

question

For the following situation, decide if the random variable described is a discrete random variable or a continuous random variable. Random variable X = the number of letters in a word picked at random out of the dictionary.

answer

Discrete random variable

question

What is the effect of an outlier on the value of a correlation coefficient?

answer

An outlier might either decrease or increase a correlation coefficient, depending on where it is in relation to the other points.

question

Which statement is not true about the 95% confidence level?

answer

The probability that the true value of the population parameter falls between the bounds of an already computed confidence interval is roughly 95%.

question

Decide if the sample is representative (or not) of the population for the question of interest. question of interest. Question: Average age of people in Salt Lake City. Sample: 10 people picked randomly from all people living in Salt Lake City. Population: All people living in Salt Lake City.

answer

Representative

question

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects one class among all the foreign language classes taught that year, and then interviews all students in that class, the sampling method is a

answer

cluster sample.

question

For the following situation, is the given percent a statistic or a parameter? 75% of all students at a school are in favor of more bicycle parking spaces on campus.

answer

Parameter

question

Joan is in charge of testing a new drug for pain relief. She administers the drug to 100 randomly selected patients who are experiencing a variety of pain symptoms. She is excited by the results that 80% of them experience pain relief in the first 2 hours while on the medication. What is wrong with Joan's study?

answer

she did not have a control to measure the placebo effect

question

Decide if the study is an observational study or an experiment. A biologist measured the increasing amounts of phosphorus in Lake Erie and observed a decreasing number of lake trout over a 5-year period.

answer

Observational Study

question

Which of the following is true about the use of sample surveys?

answer

Data from people in the sample are used to gain information about the population

question

Which one of the following statistics would be affected by an outlier?

answer

Standard deviation

question

Statistic is to sample as parameter is to

answer

population

question

To determine the average price for a gallon of regular unleaded gasoline in Central Pennsylvania, a researcher recorded the posted prices at 32 gas stations. She found that the average for her sample was $3.28 per gallon.

answer

1 sample t-test

question

Decide if the study was a retrospective or prospective study. A case-control study found higher exposure to gases, dusts, and fumes in the workplace among patients with bronchitis (an inflammation of the lungs) than among patients without bronchitis.

answer

Retrospective

question

for the following study, decide if the two samples are independent samples or paired samples. A study compared the average number of courses taken by a random sample of 100 freshmen at a university with the average number of courses taken by a separate random sample of 50 freshmen at a community college.

answer

Independent samples

question

What is the proper notation for the mean of a population?

answer

?

question

A restaurant manager is interested in analyzing whether or not there is a difference in the proportion of people who use drive-thru windows at fast food restaurants based on gender.

answer

2 proportion z-test

question

Which one of the following statements is most correct about a skewed dataset?

answer

The mean and median will usually be different.

question

What is the primary purpose of a statistical significance test?

answer

to decide between two statements made about a population parameter

question

The value of a correlation is reported by a researcher to be r = -0.5. Which of the following statements is correct?

answer

The x-variable explains 25% of the variability in the y-variable

question

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. This is a randomized experiment rather than an observational study because

answer

the participants were randomly assigned to either walk or read, rather than choosing their own activity.

question

Suppose that a 95% confidence interval for the proportion of first-year students at a school who played in intramural sports is 35% plus or minus 5%. The margin of error for the confidence interval is

answer

5% (none of these choices, 35%, 95%)

question

Tallies and cross-tabulations are used to summarize which of these variable types?

answer

Categorical

question

Which of the following is not a component of "Statistics" as defined in Chapter 1?

answer

Procedures and principles for turning uncertainty into certainty

question

A restaurant manager is interested in analyzing whether or not there is a difference in the proportion of people who use drive-thru windows at fast food restaurants based on gender.

answer

2 proportion z-test

question

Which statement is not true about the 95% confidence level?

answer

The probability that the true value of the population parameter falls between the bounds of an already computed confidence interval is roughly 95%.

question

A cola-tasting experiment is conducted in which 100 people are each given a half-cup of Cola A and a half-cup of Cola B. All 100 participants taste both colas and then rate the taste of each cola on a 0 (horrible) to 50 (tastes great) scale. For each person, a coin is tossed to determine the order of tasting the two colas. To estimate the mean difference between ratings of the two products, what procedure should be used?

answer

A paired t (or 1-sample t) confidence interval for a mean difference.

question

A p-value of 0.037 would _____________.

answer

be significant at the ? =0.05 level, but not significant at the ? = 0.01 level

question

In a hypothesis test the decision was made to not reject the null hypothesis. Which type of mistake could have been made?

answer

Type 2.

question

In a survey, students are asked how many hours they study in a typical week. A five-number summary of the responses is: 2, 9, 14, 20, 60. Fill in the blank in the following sentence. About 75% of the students spent at least ____ hours studying in a typical week.

answer

9 (14, 20, 45)

question

The head circumference (in centimeters) of 15 college-age males was obtained, resulting in the following measurements: 55, 56, 56, 56.5, 57, 57, 57, 57.5, 58, 58, 58, 58.5, 59, 59, 63. If the last measurement (63 cm's) were incorrectly recorded as 73, which one of the following statistics would change?

answer

Standard deviation

question

A statistics class has 4 teaching assistants (TAs): three female assistants (Lauren, Rona, and Leila) and one male assistant (Josh). Each TA teaches one discussion section. A student picks a discussion section. The two events W = {the TA is a woman} and J = {the TA is Josh} are

answer

disjoint (mutually exclusive) events.

question

For the following situation, decide if the random variable described is a discrete random variable or a continuous random variable. Random variable X = the weight (in pounds) a dieter will lose after following a two week weight loss program.

answer

Continuous random variable

question

The result of an Internet poll was reported as evidence that most people believe the pledge of allegiance is constitutional. The poll was conducted by posting a notice at a website and asking people to respond. The results were based on 235 people who responded. Of the 235 people, 172 (73%) believed that the pledge is constitutional, while 63 (27%) believed that the pledge is unconstitutional. The results of this poll

answer

cannot be generalized, because the results are based on a self-selected sample.

question

A group of adults aged 20 to 80 were tested to see how far away they could first hear an ambulance coming towards them. An equation describing the relationship between distance (in feet) and age was found to be: Distance = 600 - 3 Age Estimate the distance for an individual who is 20 years old.

answer

600 - 3*20

question

A statistically significant relationship between two categorical variables is illustrated in the sample as one that

answer

is large enough that it is unlikely to have occurred in the observed sample if there is no relationship in the population

question

For the following study, decide if the two samples are independent samples or paired samples. A group of 50 students each measured the length of their right arm and the length of their left arm. The average right arm lengths were compared to the average left arm lengths.

answer

Paired samples

question

A group of adults aged 20 to 80 were tested to see how far away they could first hear an ambulance coming towards them. An equation describing the relationship between distance (in feet) and age was found to be: Distance = 600 - 3 Age Based on the equation, what is the direction of the association between distance and age?

answer

Negative

question

In a survey, students are asked how many hours they study in a typical week. A five-number summary of the responses is: 2, 9, 14, 20, 60. Which interval describes the number of hours spent studying in a typical week for about 50% of the students sampled?

answer

9 to 20

question

A researcher asked random samples of 50 kindergarten teachers and 50 12th grade teachers how much money they spent out-of-pocket on school supplies in the previous school year, to see if teachers at one grade level spend more than the other. A 95% confidence interval for 1 - 2 is $30 to $50, where 1 and 2 are the population means for the amounts spent by kindergarten and 12th grade teachers, respectively. Based on this result, it is reasonable to conclude that

answer

kindergarten teachers spend more on average than do 12th grade teachers

question

A regression between foot length (response variable in cm) and height (explanatory variable in inches) for 33 students resulted in the following regression equation: y-hat = 10.9 + 0.23 x One student in the sample was 73 inches tall with a foot length of 29 cm. The predicted foot length is 27.69 cm. What is the residual for this student?

answer

29 - 27.69 cm

question

Consider an experiment that involves repeatedly rolling a six-sided die. Which of the following is a binomial random variable?

answer

The number of times that a "4" is rolled when the die is rolled six times.

question

The following is the descriptive statistics for the daily low temperatures (in degrees Fahrenheit) for Philadelphia from each day in December 1997. Variable=Low temp, N=31, Mean=31.548, Median=32, StDev=4.501, Min=21, Max=41, Q1=29, Q3=34. What percent of the days had a low temperature between 21 and 34 degrees?

answer

75%

question

Which one of these variables is a categorical variable

answer

Opinion about legalization of marijuana (Weight of a person, Height of a person, Number of ear pierces a person has)

question

Which one of these statistics is unaffected by outliers?

answer

Interquartile range

question

What is the primary purpose of a 95% confidence interval for a mean?

answer

to estimate a population mean

question

The head circumference (in centimeters) of 15 college-age males was obtained, resulting in the following measurements: 55, 56, 56, 56.5, 57, 57, 57, 57.5, 58, 58, 58, 58.5, 59, 59, 63. If the last measurement (63 cm's) were incorrectly recorded as 73, which one of the following statistics would change?

answer

Standard deviation

question

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. The two treatments in this study were

answer

walking for half an hour three times a week and reading a book for half an hour three times a week.

question

Two variables have a positive association when

answer

the values of one variable tend to increase as the values of the other variable increase.

question

The heights of a random sample of 100 women are recorded. The sample mean is 65.3 inches and the sample standard deviation is 3 inches. Which of the following is an approximate 95% confidence interval for the population mean?

answer

65.3 ± (2)(0.3)

question

According to a recent Gallup poll, about 60% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older, conducted March 30-April 2, 2001. The margin of error was reported to be 3.5%. Which of the following statements correctly interprets the reported margin of error of 3.5%?

answer

In about 95% of all random samples of this size from the same population, the difference between the sample percent and the population percent will be less than 3.5%.

question

Null and alternative hypotheses are statements about

answer

population parameters

question

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia selects every 100th student from a list of 2000 students who took a foreign language that year, the sampling method is a

answer

systematic sample.

question

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects 20 students among all students taking a foreign language class that year, the sampling method is a

answer

simple random sample

question

Decide if the study was a retrospective or prospective study. A difficult birth may put a baby at greater risk for autism, according to a study that may provide clues to the causes of the devastating neurological disability. The Centers for Disease Control and Prevention said that in a study of 698 Danish children who had the developmental disorder (autism), researchers found a disproportionately high number had been born before the 35th week of pregnancy, had suffered from low birth weights and were in a breech position at birth.

answer

Retrospective

question

Which one of the following is not appropriate for studying the relationship between two quantitative variables?

answer

Bar chart

question

When we reject our null hypothesis, which of the following errors could be made?

answer

Type 1

question

Which of the following would indicate that a dataset is skewed to the right?

answer

The mean is much larger than the median.

question

Michael wants to take French or Spanish, or both. But classes are closed, and he must apply and get accepted to be allowed to enroll in a language class. He has a 50% chance of being admitted to French, a 50% chance of being admitted to Spanish, and a 20% chance of being admitted to both French and Spanish. If he applies to both French and Spanish, the probability that he will be enrolled in either French or Spanish (or possibly both) is

answer

80%

question

Student grade point averages (GPAs) are calculated by assigning a number to each letter grade earned, with A = 4, B = 3, C = 2, D = 1 and F = 0, then finding the average. A student proposes using the median of the numbers instead and calls this medGPA. A student has taken five courses (all an equal number of credit hours) and the grades were A, A, F, B, A. The usual GPA for these grades is 3.0. Should the student prefer using the median (medGPA)?

answer

Yes, because medGPA is A = 4.0 for this student.

question

In the language of statistics, the null hypothesis is a statement that ____.

answer

nothing is happening.

question

A null hypothesis is that the probability is 0.7 that a new drug will provide relief in a randomly selected patient. The alternative is that the probability of relief is greater than 0.7. Suppose the treatment is used on 500 patients and there are 380 successes. How would a p-value be calculated in this situation?

answer

Find the chance of 380 or more successes, calculated assuming the true success rate is 0.7.

question

An experimenter wants to determine if women are more likely than men to cooperate when asked questions by a door-to-door poll taker. 143 out of 250 women sampled cooperated, while 97 out of 175 men cooperated.

answer

2 proportion z-test

question

Which of the correlation coefficients below indicates the strongest relationship?

answer

r = -0.80

question

If one card is randomly picked from a standard deck of 52 cards, the probability that the card will be a number from 2 through 10, or a Heart, or both, is

answer

76.9% (40/52)

question

Students who live in the dorms at a college get free T.V. service in their rooms, but only receive 6 stations. On a certain evening, a student wants to watch T.V. and the six stations are broadcasting separate shows on baseball, football, basketball, local news, national news, and international news. The student is too tired to check which channels the shows are playing on, so the student picks a channel at random. On a different night, two students who don't know each other each choose a channel this way. The two events, N = {the first student watches a news broadcast} and F = {the second student watches football} are

answer

independent events

question

Which one of the following variables is not categorical?

answer

Age of a person

question

Weights of females have approximately a normal distribution with mean 135 lbs. and standard deviation 20 lbs. Allison weighs 145 lbs. What is the z-score for her weight?

answer

(145 - 135) / 20

question

A hypothesis test gives a p-value of 0.050. If the significance level ? = 0.05, the results are said to be

answer

statistically significant because the p-value ? ?.

question

Which of the following describes the relationship between the Central Limit Theorem and the Rule for Sample Proportions?

answer

The Rule for Sample Proportions follows from the Central Limit Theorem by defining each observation in the sample to be either 1 or 0.

question

A computer awareness test was administered on the first day of a computer science course. The professor was interested in seeing if students who had previously taken a high school computer course scored higher than students with no previous computer coursework. In his class, 15 students had taken a high school computer course and 22 students had never taken a computer course.

answer

2 sample t-test

question

To determine the average price for a gallon of regular unleaded gasoline in Central Pennsylvania, a researcher recorded the posted prices at 32 gas stations. She found that the average for her sample was $3.28 per gallon.

answer

1 sample t-test

question

In hypothesis testing, a Type 1 error occurs when

answer

the null hypothesis is rejected when the null hypothesis is true.

question

Students who live in the dorms at a college get free T.V. service in their rooms, but only receive 6 stations. On a certain evening, a student wants to watch T.V. and the six stations are broadcasting separate shows on baseball, football, basketball, local news, national news, and international news. The student is too tired to check which channels the shows are playing on, so the student picks a channel at random. The two events F = {the student watches football} and A = {the student watches an athletic event} are

answer

None of these ( independent events, each simple events, disjoint (mutually exclusive) events )

question

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. If a statistically significant difference in blood pressure change at the end of a year for the two activities was found, then

answer

it can be concluded that the difference in activity caused a difference in the change in blood pressure.

question

A survey based on a random sample of 1000 students found that 1% of these students, when asked by the professor doing the survey, admitted to having cheated on at least one exam. The results of this study, if applied to all students in the university, are questionable because of

answer

response bias.

question

In hypothesis testing, a Type 2 error occurs when

answer

the null hypothesis is not rejected when the alternative hypothesis is true.

question

In the study described in Case Study 1.4, questionnaires were sent to 100,000 women asking about love, sex and relationships. Only 4.5% of the women responded. This means that

answer

nonresponse bias was likely to be a major problem.

question

A random sample of 60 mathematics majors spent an average of $200.00 for textbooks for a term, while a random sample of 40 literature majors spent an average of $180.00 for textbooks that term. The standard deviation for each sample was $20.00. The standard error for the difference between the two sample means is 4.082. Calculate an approximate 95% confidence interval for the difference in average amounts spent on textbooks (math majors -literature majors).

answer

(200 - 180) ± 2*4.082

question

What is the primary purpose of a statistical significance test?

answer

to decide between two statements made about a population parameter

question

Which statement is correct about a p-value?

answer

The smaller the p-value the stronger the evidence in favor of the alternative hypothesis.

question

A five-number summary given in Case Study 1.1 for the fastest ever driving speeds reported by 102 women was: 30, 80, 89, 95, 130. Fill in the blank in the following sentence: Approximately 25% of the women reported a fastest ever driving speed of at most _____ mph.

answer

80

question

Which statement is not true about confidence intervals?

answer

A confidence interval between 20% and 40% means that the population proportion lies between 20% and 40%.

question

The number of seagulls on a beach is an example of a(n) ____________ variable.

answer

discrete

question

A five-number summary for a data set is 35, 50, 60, 70, 90. About what percent of the observations are between 35 and 90?

answer

100%

question

A regression between foot length (response variable in cm) and height (explanatory variable in inches) for 33 students resulted in the following regression equation: y-hat = 10.9 + 0.23 x What is the estimated average foot length for students who are 70 inches tall?

answer

10.9 + 0.23 (70)

question

Suppose you were to read about a study showing that people who sleep less than five hours a night have twice as much risk of a premature death as people who sleep seven or eight hours a night. Which of the following is not an example of a possible "confounding variable" in this study?

answer

The amount of sleep a person gets per night.

question

A hypothesis test for a population proportion p is given below: Ho: p ? 0.40 Ha: p < 0.40 For the given z-statistic, calculate the p-value for this hypothesis test. z-statistic = -1.50. p-value = ?

answer

0.0668

question

A table is given below involving probabilities about a random variable X: ....k__0____1___2____3____4___5___6 ____ .04__.30__.50__.61__.72__.83__1.00

answer

The table is for a cumulative probability distribution (CDF).

question

A hypothesis test for a population proportion p is given below: Ho: p ? 0.40 Ha: p < 0.40 For the given z-statistic, calculate the p-value for this hypothesis test. z-statistic = 0.50. p-value = ?

answer

0.6915

question

Which one of the following statements is false?

answer

The sampling distribution of the sample mean is exactly normal if the observations are normally distributed.

question

The simple linear regression equation can be written as y-hat = b0+b1x In the simple linear regression equation, the symbol b0 represents the

answer

estimated intercept.

question

Students who live in the dorms at a college get free T.V. service in their rooms, but only receive 6 stations. On a certain evening, a student wants to watch T.V. and the six stations are broadcasting separate shows on baseball, football, basketball, local news, national news, and international news. The student is too tired to check which channels the shows are playing on, so the student picks a channel at random. On a different night, two students who don't know each other each choose a channel this way. The two events, N = {the first student watches a news broadcast} and F = {the second student watches football} are

answer

independent events.

question

Tallies and cross-tabulations are used to summarize which of these variable types?

answer

Categorical

question

A group of adults aged 20 to 80 were tested to see how far away they could first hear an ambulance coming towards them. An equation describing the relationship between distance (in feet) and age was found to be: Distance = 600 - 3 Age How much does the estimated distance change when age is increased by 1?

answer

It goes down by 3 feet.

question

A restaurant manager is interested in analyzing whether or not there is a difference in the proportion of people who use drive-thru windows at fast food restaurants based on gender.

answer

2 proportion z-test

question

Pulse rates of adult men are approximately normal with a mean of 70 and a standard deviation of 8. Which choice correctly describes how to find the proportion of men that have a pulse rate greater than 78?

answer

Find the area to the right of z =1 under a standard normal curve.

question

A null hypothesis is that the probability is 0.7 that a new drug will provide relief in a randomly selected patient. The alternative is that the probability of relief is greater than 0.7. Suppose the treatment is used on 500 patients and there are 380 successes. How would a p-value be calculated in this situation?

answer

Find the chance of 380 or more successes, calculated assuming the true success rate is 0.7.

question

An organization would like to conduct a survey of a sample of their membership to make conclusions about the entire membership. Given that they have a limited budget, they should focus their attention on

answer

getting a representative sample.

question

Decide if the study is an observational study or an experiment. Twenty blue-fin tuna were randomly assigned to two tanks of water, 10 tuna in each tank. One tank was polluted with methyl mercury, while the other tank was not polluted. The survival times of the fish in the two tanks were compared.

answer

Experiment

question

A hypothesis test gives a p-value of 0.03. If the significance level ? = 0.05, the results are said to be

answer

statistically significant because the p-value ? ?.

question

The statistical significance of the association or relationship between two categorical variables is examined using a value known as the chi-square statistic, and a corresponding p-value that assesses the chance of getting this value for the Chi-square statistic or one even larger. Suppose the p-value of the test turns out to be 0.18. In this case, we should decide that

answer

the observed relationship could have occurred by chance, so we cannot say that the relationship is statistically significant.

question

If, in a hypothesis test, the null hypothesis is actually true, which type of mistake can be made?

answer

Type 1.

question

Null and alternative hypotheses are statements about

answer

population parameters.

question

The cholesterol levels of a random sample of 100 men are measured. The sample mean is 188 and the sample standard deviation is 40. Which of the following provides a 95% confidence interval for the population mean?

answer

188 ± (1.98)(4)

question

What is the primary purpose of a 95% confidence interval for a mean?

answer

to estimate a population mean

question

According to a recent Gallup poll, about 60% of all American adults owned a cell phone at the time of the poll. The results are based on telephone interviews with a randomly selected national sample of 998 adults, 18 years and older, conducted March 30-April 2, 2001. The margin of error was reported to be 3.5%. Which of the following statements correctly interprets the reported margin of error of 3.5%?

answer

In about 95% of all random samples of this size from the same population, the difference between the sample percent and the population percent will be less than 3.5%.

question

A hypothesis test for a population proportion p is given below: Ho: p = 0.70 Ha: p ? 0.70 For the givenz-statistic, calculate the p-value for the hypothesis test. z-statistic = 0.40. p-value = ?

answer

0.6892

question

Decide if the study is an observational study or an experiment. A biologist measured the increasing amounts of phosphorus in Lake Erie and observed a decreasing number of lake trout over a 5-year period.

answer

Observational Study

question

Which one of these variables is a categorical variable?

answer

Opinion about legalization of marijuana

question

A 95% confidence interval for the difference in the population proportions of men (group 1) and women (group 2) who exercise regularly, is [-0.06 to +0.10]. Which of the following is not a reasonable conclusion from this confidence interval?

answer

It is plausible that men spend 10% more time exercising, on average, than do women.

question

Ultrasound is a procedure used by physicians to examine the fetus of a pregnant woman. An observational study found that the average birthweight of infants whose mothers who had used ultrasound was lower than the average birthweight of infants whose mothers had not. One confounding variable for this study was

answer

women having problems with their pregnancies were more likely to choose an ultrasound than women without pregnancy problems.

question

A list of 5 pulse rates is: 70, 64, 80, 74, 92. What is the median for this list?

answer

74

question

Consider an experiment that involves repeatedly rolling a six-sided die. Which of the following is a binomial random variable?

answer

The number of times that a "4" is rolled when the die is rolled six times.

question

Which statement is correct about a p-value?

answer

The smaller the p-value the stronger the evidence in favor of the alternative hypothesis.

question

The time taken for a computer to boot up, X, follows a normal distribution with mean 30 seconds and standard deviation 5 seconds. What is the standardized score (z-score) for a boot-up of time x = 35 seconds?

answer

1

question

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects one class among all the foreign language classes taught that year, and then interviews all students in that class, the sampling method is a

answer

cluster sample.

question

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. This is a randomized experiment rather than an observational study because

answer

the participants were randomly assigned to either walk or read, rather than choosing their own activity.

question

The regression line for a set of points is given by y-hat = 12 - 6 x. What is the slope of the line?

answer

-6

question

Which of the following statements is NOT true about the p-value?

answer

The p-value represents the probability of getting a test statistic more extreme than our sample result assuming the alternative hypothesis is true.

question

If one card is randomly picked from a standard deck of 52 cards, the probability that the card will be a number from 2 through 10, or a Heart, or both, is

answer

76.9% (40/52)

question

A statistics class has 4 teaching assistants (TAs): three female assistants (Lauren, Rona, and Leila) and one male assistant (Josh). Each TA teaches one discussion section. A student picks a discussion section. The two events W = {the TA is a woman} and M = {the TA is a man} are

answer

disjoint (mutually exclusive) events.

question

Olivia wants to learn a foreign language. To get an idea of how satisfied other students were after taking a foreign language course, she decides to take a random sample of 20 students. If Olivia randomly selects 20 students among all students taking a foreign language class that year, the sampling method is a

answer

simple random sample.

question

When we reject our null hypothesis, which of the following errors could be made?

answer

Type 1

question

The result of an Internet poll was reported as evidence that most people believe the pledge of allegiance is constitutional. The poll was conducted by posting a notice at a website and asking people to respond. The results were based on 235 people who responded. Of the 235 people, 172 (73%) believed that the pledge is constitutional, while 63 (27%) believed that the pledge is unconstitutional. The results of this poll

answer

cannot be generalized, because the results are based on a self-selected sample

question

An experiment is usually preferred to an observational study because

answer

one can draw a cause and effect conclusion in an experiment but not in an observational study.

question

For the following question, calculate the standard error of the sample statistic. A randomly selected sample of 100 students had an average grade point average (GPA) of 3.2 with a standard deviation of 0.2 The standard error of the sample mean is

answer

0.2 / square root (100)

question

In the language of statistics, the null hypothesis is a statement that ____.

answer

nothing is happening

question

The average salaries of professors at public institutions are compared to see if there is a difference in average earnings between the genders.

answer

2 sample t-test

question

One of the common elements of the seven case studies in Chapter 1 is

answer

in each case, data are used to make a judgment about the situation.

Stat 200 Final Practice Exam

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards