# Math Probability study guide

What is the probability of rolling an even number on a normal die? Write as a simplified fraction
3/6=½

Even # on a dice

What is the probability of rolling an even number on a normal die? Write as a decimal.
3/6=½

1÷2= .5

What is the probability of rolling an even number on a normal die? Write as a percent
3/6=½

1÷2= .5 = 50%

What is the probability of drawing a diamond from a deck of cards? Write as a simplified fraction
52 total cars; 4 suit; 13 cards of each suit
13/52= 1/4

What is the probability of drawing a diamond from a deck of cards? Write as a decimal
13/52= 1/4

1÷4= .25

What is the probability of drawing a diamond from a deck of cards? Write as a percent
13/52= 1/4

1÷4= .25= 25%

Ryan went to the library and borrowed 10 books, which he put in a bag. 3 were fantasy books, 2 were biographies, 1 was a Sci-Fi book, and 4 were historical accounts of events. What is the probability that if he reached in the bag, he would draw out a biography? Write as a fraction.
2/10= 1/5

Ryan went to the library and borrowed 10 books, which he put in a bag. 3 were fantasy books, 2 were biographies, 1 was a Sci-Fi book, and 4 were historical accounts of events. What is the probability that if he reached in the bag, he would draw out a Sci-Fi book? Write as a decimal.
1/10
1÷10= 0.1

9. Ryan went to the library and borrowed 10 books, which he put in a bag. 3 were fantasy books, 2 were biographies, 1 was a Sci-Fi book, and 4 were historical accounts of events. What is the probability that if he reached in the bag, he would draw out a fiction book? Write as a percent
4/10= .4= 40%

Ryan went to the library and borrowed 10 books, which he put in a bag. 3 were fantasy books, 2 were biographies, 1 was a Sci-Fi book, and 4 were historical accounts of events. What is the probability that if he reached in the bag, he would draw out a non-fiction book? Write as a decimal
6/10= .6

Ryan went to the library and borrowed 10 books, which he put in a bag. 3 were fantasy books, 2 were biographies, 1 was a Sci-Fi book, and 4 were historical accounts of events. What is the probability that he would draw the two biographies (without replacing the one he first one he drew out)?
2/10 × 1/9= 2/90= 1/45

What is the probability of a die being rolled 4 times and always landing on either a 2 or a 4?
rolling a dice 4 times
P(lands on 2 or 4 each time)
2/6= 1/3
1/3 × 1/3 × 1/3 × 1/3= 1/81

Jane has 3 shirts, 4 pairs of pants and 8 pairs of shoes. How many different combinations of outfits can she make?
3 × 4 × 8= 96

Jane has 3 shirts, 4 pairs of pants and 8 pairs of shoes. 3 of the shirts are black, 1 pair of pants is black and 2 pairs of shoes are black. What is the probability that she will select an outfit that is all black?
1/16

There are 5 marbles. Two are blue, one is black and two are green. What is the probability of drawing a black marble and then a green marble (without replacing the first one he drew out)?
1/5 × 2/4= 1/5 × 1/2=

1/10

John has 5 shapes (circle, square, triangle, rectangle, trapezoid) and he has to color each one a different color. If he has 7 different colors to work with (yellow, orange, blue, pink, purple, red, green), how many different possible ways could he color them?
7 × 5= 35

John has 5 shapes (circle, square, triangle, rectangle, trapezoid) and he has to color each one a different color. If he has 7 different colors to work with (yellow, orange, blue, pink, purple, red, green). What is the probability that the trapezoid is painted red?
trap is red= 1/7

John has 5 shapes (circle, square, triangle, rectangle, trapezoid) and he has to color each one a different color. If he has 7 different colors to work with (yellow, orange, blue, pink, purple, red, green). What is the probability that the trapezoid is painted red and the circle is painted black?
no black so zero; 0

John has 5 shapes (circle, square, triangle, rectangle, trapezoid) and he has to color each one a different color. If he has 7 different colors to work with (yellow, orange, blue, pink, purple, red, green). What is the probability that the circle is painted blue and the rectangle is painted either green or red?
1/7 × 2/6= 2/42=

1/21