statistic – Space

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DM Statistics
Exercise 1:
The automobile industry sold 657,000 vehicles in the United States during January 2009 (The
Wall Street Journal, February 4, 2009). This volume was down 37% from January 2008 as
economic conditions continued to decline. The Big Three U.S. automakers‚ÄĒ General Motors,
Ford, and Chrysler‚ÄĒsold 280,500 vehicles, down 48% from January 2008. A summary of
sales by automobile manufacturer and type of vehicle sold is shown in the following table.
Data are in thousands of vehicles. The non-U.S. manufacturers are led by Toyota, Honda, and
Nissan. The category Light Truck includes pickup, minivan, SUV, and crossover models.


 Type of Vehicle
Non U.S.Light Truck
a. Develop a joint probability table for these data and use the table to answer the
remaining questions.
Type of Vehicle
CarLight Truck87.4193.1280.5Non U.S.228.5148.0376.5TOTAL315.9341.1657.0U.S.
A total of 657.0 thousand vehicles were sold.
Dividing each entry in the table by 657.0 provides the following joint probability table.
Type of Vehicle
U.S.0.13300.29390.4269Non U.S.0.34780.22530.5731TOTALManufacturerLight TruckTOTAL0.48080.51921.0000FOUASSON
  b. What are the marginal probabilities? What do they tell you about the
probabilities associated with the manufacturer and the type of vehicle soldU= U. S. manufacturer
N= Non U.S. manufacturer
C= Car
L= Light Truck
Marginal probabilities : P(U)=0.1330+0.2939= 0.4269
P(B)=0.3478+0.2253= 0.5731
There a higher probability that the vehicle was not manufactured by a U.S auto maker. In
terms of market share, non US. Auto…

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