Carla Espinosa, staff research assistant with Market Research Associates, Ltd., has conducted a survey of households in the Coral Gables part of the Greater Miami area. The focus of Espinosa’s survey is to gain information on the buying habits of potential customers for a local new car dealership. Among the data collected by Espinosa is the following information on number of cars per household and household disposable income for a sample of n = 15 households:

Number            Household

of Cars                Income

         (in $000)

1 ………………………….100

3 ………………………….100

0 ………………………….30

2 ………………………….50

0 ………………………….30

2 ………………………….30

2 ………………………….100 

0 ………………………….30

2 ………………………….100 

2 ………………………….50

3 ………………………….100 

2 ………………………….50

1 ………………………….50

1 ………………………….30

2 ………………………….50

A. Calculate the mean, median, and mode measures of central tendency for the number of cars per household and household disposable income. Which measure does the best job of describing central tendency for each variable?

B. Based on this n = 15 sample, calculate the range, variance, and standard deviation for each data series, and the 95 percent confidence interval within which you would expect to find each variable’s true population mean.

C. Consulting a broader study, Espinosa found a $60,000 mean level of disposable income per household for a sample of n = 196 Coral Gables households. Assume Espinosa knows that disposable income per household in the Miami area has a population mean of $42,500 and σ = $3,000. At the 95 percent confidence level, can you reject the hypothesis that the Coral Gables area has a typical average income?