QUESTION 5

What is the sample size so that, when using parametric two-tailed z-test (or t-test) for mean for one population, one can have a 90% power to detect an difference in mean that is 1/4 of the standard deviation of the population under the null hypothesis at 5% level of significance? (Check one choice below that is closest to your answer.)

	A.	169
	B.	126
	C.	138
	D.	208

QUESTION 1

Which of the following statements is correct about confidence interval estimation for mean of a population using t-distribution?

	A.	Sample has to be from normally distributed population regardess of sample size.
	B.	The larger the standard deviation of the populatoin the smaller the margin of error.
	C.	Increase confidence level will increase the margin of error.
	D.	Increase the sample size will increase the margin of error.