Multiple Choice

1. Compare the results of the large sample with the results from the small sample and explain what they mean.
a. As the sample size gets larger, the interval decreases. We become more confident that the mean will lie in our interval.
b. As the sample gets larger, the interval increases. We become more confident that the mean will be lie in our interval
c. It does not matter if the sample gets larger. The mean will always lie in our interval.

2. When estimating the population mean, you will derive an interval in which we are 100% sure the population mean falls.
a. True
b. False

3. The confidence level you choose when you are estimating the population mean:
a. depends on how certain you want to be that the population mean falls within a certain distance of the sample mean.
b. determines a critical value zc
c. absolutely guarantees that the true value of the population mean is within a certain interval around the sample mean.
d. a and b are correct
e. b and c are correct

4. If all other factors remain the same, increasing the sample size of an experiment will decrease the magnitude of the error of estimate.
a. True
b. False

5. When you are calculating a confidence interval, the sample mean plays a significant role in determining the error of estimate.
a. True
b. False

6. A researcher tests a sample mean against a standard known value (such as a calibration value), and reports df = 15. How many subjects were in the sample?
a. 30
b. 14
c. 16
d. Cannot be determined from the information given.

7. Given the following information about a statistical experiment find the value of E. sample size = 64, s = 4.71, confidence level = 95%
a. 1.154
b. 0.184
c. .380
d. 1.332

8. As you increase an experiment's sample size:
a. the shape of the t distribution remains unchanged
b. the shape of the t distribution gets flatter
c. the shape of the t distribution becomes more and more like that of the normal distribution
d. none of the above

9. If you keep the same n but increase the level of confidence from 95% to 99%, the width of your confidence interval will . . .
a. narrow
b. remain the same
c. widen
d. cannot do this without changing n

11. Find the tc for a 90% confidence level with a sample size of 18.

12. Use Norman's mean weight of 46.2 lbs. and standard deviation of 2.5lbs. of flour. Determine a confidence interval for the mean weight of flour needed using a sample of 26 loaves. Use a confidence level of 90%.