1. The probability that a standard normal variable Z is positive is

a) 0.5

b) 0.75

c) 1

d) 0

2. A 95% confidence interval estimate for the difference between two population means, is determined to be (62.75, 68.52.) If the confidence level is reduced to 90%, the confidence interval

a) becomes narrower

b) more information is needed

c) becomes wider

d) remains the same

3. If a hypothesis is rejected at the 0.025 level of significance, it:

a) May Or May Not Be Rejected At The 0.01 Level

b) Must Be Rejected At Any Level

c) Must Be Rejected At The 0.01 Level

d) Must Not Be Rejected At The 0.01 Level