Suppose the number of equipment sales and service contracts that a store sold ...

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 questions in the space provided 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?