The weekly study times for all students in a school are normally distributed with μ = 18 hours and σ = 6 hours. If 36 students are randomly selected, find the probability that their mean study time is greater than 20 hours. My work: 20-18/(6/√36)=2/(6/6)=2/1=2 .4772 47.72% probability that their mean study time is greater than 20 hours. But answer should be 62.93.

Answer 1

Probability answer never > 1.

If Z = 2, P > 2 = .0228