1. ## Help. Have answer but teacher says wrong.

A study of 500 pastors in the Baptist Church found that their sermons lasted an average of 20 minutes with a standard deviation of 3 minutes. If a sample of 50 pastors is selected, what is the probability that their sermons will average more than 21 minutes?

21-20
3/√50
=2.36

Z> 2.36 = .0091

My teacher said the z score is correct but the probability is not .0091 but .86 and I don't understand what I'm doing wrong.

2. your instructor is wrong, it's .0091.

3. I can also confirm your instructor is wrong, I just checked the normal table in my text and you're dead on.

4. Originally Posted by Oasis
A study of 500 pastors in the Baptist Church found that their sermons lasted an average of 20 minutes with a standard deviation of 3 minutes. If a sample of 50 pastors is selected, what is the probability that their sermons will average more than 21 minutes?

21-20
3/√50
=2.36

Z> 2.36 = .0091

My teacher said the z score is correct but the probability is not .0091 but .86 and I don't understand what I'm doing wrong.