1 In which of the situations below is it OK to use the z sta

1:

In which of the situations below is it OK to use the z statistic?

2:

In which of the situations below is it OK to use the t statistic?

Solution

1.

OPTION A: To test H0: = 15 mm vs Ha: > 15 mm when the sample size is 20, X is normally-distributed and is known. [ANSWER, A]

[We can use z even when the sample size is small when is known.]

******************

2.

To test H0: = 15 mm vs Ha: < 15 mm when the sample size is 35, X is normally-distributed and is estimated by s.

[We can use t when we know the data is normally distirbuted, by we do not know .]