Question

A computer manufacturer believes that its line of minicomputers has, on average, 8.2 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 5.2, with a sample standard deviation of 1.3 days. Test whether these minicomputers actually have, on average, 8.2 days of downtime in the entire population. Let α = 0.01.

Answer 1

H0: = 8.2

Ha: 8.2

Test statistics

= - / S / sqrt(n)

= 5.2 - 8.2 / 1.3 / sqrt(7)

= -6.11

This is test statistics value.

From T table,

With test statistics t = -6.11 and df = 6

p-value = 0

Since p-value < 0.01 , we have sufficient evidence to reject H0.