In Testing the Difference Between Two Population Means Using Two

Multiple Choice

In testing the difference between two population means using two independent samples,the population standard deviations are assumed to be unknown,each sample size is ? 30,and the calculated test statistic z = 2.56.If the test is two-tail and 5% level of significance has been specified,the conclusion should be to:

A) reject the null hypothesis.
B) not to reject the null hypothesis.
C) choose two other independent samples.
D) none of these answers is correct.