The branch manager of an outlet (Store 1) of a 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 as follows:

Amount of money spent: X = +21.34, S = +9.22.
Thirty-seven customers own only a dog.
Twenty-six customers own only a cat.
Seven customers own more than one dog and/or cat.
Construct a 95% confidence interval estimate for the
population mean amount spent in the pet supply store.

Construct a 90% confidence interval estimate for the population proportion of customers who own only a cat.
The branch manager of another outlet (Store 2) wishes to conduct

a similar survey in his store. The manager does not have access to

the information generated by the manager of Store 1. Answer the

following questions:

c. What sample size is needed to have 95% confidence of

estimating the population mean amount spent in this store

to within { +1.50 if the standard deviation is estimated to

be $10?

d. How many customers need to be selected to have 90% confidence of estimating the population proportion of customers who own only a cat to within {0.045?

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