Question: The branch manager of an outlet (store 1) of nationwide chain of pet supply stores wants to study characteristics of her customers. In particular, she decides to focus on two variables: the amount of money spent by customers and whether the customers own only one dog, only one cat or more than one dog and/or cat. The results from a sample of 70 customers are:

? Amount of money spent: Xbar = $21.34, S= $9.22

? 37 customers own only a dog

? 26 customers own only a cat

? 7 customers own more than one dog and/or cat

a) Construct a 95% confidence interval estimate of the population mean amount spent in the pet supply store.

b) Construct a 90% confidence interval estimate of the population proportion of customers who own only a cat.

c) What sample size is needed to have 95% confidence of estimating the population mean amount spent in his store to within +/- 1.50 if the standard deviation is $10?

d) What sample size is needed to have 90% confidence of estimating the population proportion of customers who own only a cat to within +/- .045?

e) Based on your answers to (c) and (d), how large a sample should the manager take?