Question

A laboratory technician claims that on average it takes her no more than 7.5 minutes to perform a certain task. A random sample of 20 times she performed this task was selected and the average and standard deviation were 7.9 and 1.2, respectively. At α = 0.05, does this constitute enough evidence against the technician's claim? Use the rejection point method.

Answer 1

The Hypotheses are:

Rejection region:

Reject Ho if T < -t _{0.05, 19} where 19 is the degree of freedom, n-1=20-1=19

Test statistic:

Conclusion:

Since T > t _{0.05,19 ,} hence we reject the null hypothesis and conclude that there is not sufficient evidence to support the claim.

The Table