Question

The population mean and standard deviation are given below. Find the required probability and determine whether the given sample mean would be considered unusual. For a sample of n equals 63​, find the probability of a sample mean being less than 20.2 if mu equals 20 and sigma equals 1.16.

Answer 1

Solution :

Given that ,

= 20

= / n = 1.16 / 63 = 0.146

P( < 20.2) = P(( - ) / < (20.2 - 20) / 0.146)

= P(z < 1.37)

Using z table

= 0.9147

No, it would be not unusual because more than 5% of all such samples have means less than 20.2