A random sample of 49 measurements from a population with population standard deviation σ1 = 4 had a sample mean of x1 = 11. An independent random sample of 64 measurements from a second population with population standard deviation σ2 = 5 had a sample mean of x2 = 14. Test the claim that the population means are different. Use level of significance 0.01. What distribution does the sample test statistic follow? Explain.

Reject H0 and conclude that population means are different.

Step-by-step explanation:

H0: μ1 = μ2

H1: μ1 ≠ μ2

x1 = 11 ; σ1 = 4 ; n1 = 49

x2 = 14 ; σ2 = 5 ; n2 = 64

The test statistic :

(x1 - x2) / sqrt[(σ1²/n1 + σ2²/n2)]

Test statistic :

(11 - 14) / sqrt[(4²/49 + 5²/64)]

Test statistic :

-3 / √0.7171556

Test statistic = - 3.542

Using α = 0.01

The critical value Zα/2 ; Z0.01/2 = 2.58

Decison region :

Reject H0 : if Test statistic < Zcritical

Reject H0 : - 3.542 < - 2.58