6. A confidence interval forpis given as 0.38 0.004. The value 0.004 is properly called the

1. Estimator
2. point estimate
3. critical value
4. level of confidence
5. margin of error
6. None of above

7. If a sample of sizen= 45 gives the 95% confidence interval 45 << 65, which of the following is true?

1. The 99% confidence interval forwould be wider than the one given.
2. We would expect a 95% confidence interval for based on a sample of sizen= 80 to be wider than the one given.
3. A point estimate foris 50.
4. The probability that the random variableis between 40 and 50 is 0.95.

2

8. To test that the population variance is more than 20 at the 0.1 level of

significance, we collect a sample of size 25. What is the critical value

2?

a. 8.907 b. 15.659 c. 27.204 d. 33.196

9. To study a long-distance phone service at a province, a researcher conducts a poll to estimate the percentage of consumers who are satisfied with their long-distance phone service. A previous study suggests that this percentage is about 82%. What is the smallest sample size necessary if he wants to be 95% of confident that his sample percentage is within 3.5 percentage points of the true population value?

1. 464
2. 463
3. 462
4. 461
5. None of above