Question

The 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.64.find the probability of a sample mean being less than 21.2 if μ·21and σ·1.22. 国Click the icon to view page 1 of the standard normal table. 囲Click the icon to view page 2 of the standard normal table. For a sample of n-64, the probability of a sample mean being less than 212-21 and ơ-1226 (Round to four decimal places as needed.)

Answer 1

Answer:

Population mean μ = 21 and a standard deviation σ = 1.22

We want to find the probability of a sample mean being less than 21.2

P(xbar < 21.2) = P((xbar - µ)/ (σ/√n)) < (21.2– 21)/ (1.22/sqrt(64))

             = P( Z < 1.31)

               = 0.9049 (Using Statistical table)

The probability is 0.9049

The given sample mean being less than 21.2 would be considered unusual because it has less than 90% probability.