1. The true sampling error is usually not known because

a. The population mean is unknown

b. The population mean is a random sample

c. The variance is unknown

d. The standard deviation is unknown

2. Mileage tests were conducted on a randomly selected sample of one hundred newly developed truck tires. The average tread wear was found to be 50,000 miles with a standard deviation of 3,500 miles. What is the best estimate of the average tread life for the entire population of these truck tires?

a. 50,000 miles

b. 3,500 miles

c. 5,000 miles

d. 53,500 miles

3. If the size of the sample is increased from 10 respondents to 20 respondents, the standard error of the mean will

a. increase

b. decrease

c. remain the same

d. The result is not predictable

4. If a population follows the normal distribution, what will be the shape of the distribution of sample means?

a. The distribution of the sample means will be positively skewed

b. The distribution of sample means will be negatively skewed

c. The distribution of sample means will always be symmetrical

d. The distribution of the sample means will represent a normal distribution

5. Which of the following would be employed as a point estimate for the population mean?

a. the population standard deviation

b. the sample mean divided by the sample mean

c. the sample mean

d. the sample standard deviation

6. For a given confidence interval, what is the interpretation of 96% confidence level?

a. There is a 96% chance that the given interval includes the true value of the population parameter

b. Approximately 96 out of 100 such intervals would contain the true value of the population parameter

c. The is a 4% chance that given interval includes the true value of the population parameter

d. Both (a) and (b) are correct

7 Which statement(s) is/are correct about the t distribution?

a. The mean is equal to zero

b. The t distribution is symmetric

c. The t distribution is based on degrees of freedom

d. All of the above statements are correct

8. A random sample of twenty items is selected from a population. To determine the appropriate critical t-value, what number of degrees of freedom should be employed?

a. 19

b. 20

c. 21

d. 25