BUSINESS STATISTICS 9

Suppose the number of equipment sales and service contracts that a store sold during the last six (6) months for treadmills and exercise bikes was as follows:                             

                                    Treadmill          Exercise Bike

 Total sold                   185                           123 

Service contracts    67                             55  

The store can only sell a service contract on a new piece of equipment. Of the 185 treadmills sold, 67 included a service contract and 118 did not.  

Complete the following answers below: 

1) Construct a 95 percent confidence interval for the difference between the proportions of service contracts sold on treadmills versus exercise bikes. 

2) Is there a major difference between the two pieces of equipment? Why or why not?