Question

The average number of days required by a college's undergraduate students to complete a project was 22 days in the previous year with a population standard deviation of 6. The college’s administration wishes to determine whether the average is higher this year. A sample of 20 students produced a mean of 24 days. Assume a normal distribution. Is there enough evidence at the 5% significance level to determine whether the mean has increased?

a. No, because the test statistic falls outside the rejection region [1.645, ?).

b. Yes, because the test statistic falls in the rejection region (-?,-1.96].

c. No, because the test statistic falls outside the rejection region [1.960, ?).

d. No, because the test statistic falls outside the rejection region [1.729, ?). e. None of the above

Answer 1

Ans:

Test statistic:

z=(24-22)/(6/sqrt(20))

z=1.49

critical z value=1.645

critical rejection region:[1.645, ?)

Option a is correct.

No, because the test statistic falls outside the rejection region [1.645, ?).