Question

A computer manufacturer estimates that its line of minicomputers has, on average, 7.2 days of downtime per year. To test this claim, a researcher contacts seven companies that own one of these computers and is allowed to access company computer records. It is determined that, for the sample, the average number of downtime days is 4.1, with a sample standard deviation of 1.5 days. Assuming that number of downtime days is normally distributed, test to determine whether these minicomputers actually average 7.2 days of downtime in the entire population. Let α = .01.

Appendix A Statistical Tables

(Round your answer to 2 decimal places.)

According to one survey taken a few years ago, 32% of American households have attempted to reduce their long-distance phone bills by switching long-distance companies. Suppose that business researchers want to test to determine if this figure is still accurate today by taking a new survey of 85 American households who have tried to reduce their long-distance bills. Suppose further that of these 85 households, 24% say they have tried to reduce their bills by switching long-distance companies. Is this result enough evidence to state that a significantly different proportion of American households are trying to reduce long-distance bills by switching companies? Let α = .01.

Appendix A Statistical Tables

(Round your answer to 2 decimal places.)

Answer 1