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=61​, find the probability of a sample mean being less than 24.6 2if mu μ equals=25 and sigma σequals=1.15

Answer 1

Solution :

Given that ,

= 25

= / n = 1.15 / 61 = 0.1472

P( < 24.62) = P(( - ) / < (24.62 - 25) / 0.1472 )

= P(z < -2.58)

Using z table

= 0.0049