Question

The following 5 questions are based on this information.

Data from the Bureau of Labor Statistics' Consumer Expenditure Survey show customers spend an average of (µ) $508 a year for cellular phone services. The standard deviation of annual cellular spending is (σ) $132. The random variable, yearly cellular spending, is denoted by X.

We plan to select a random sample of 200 cellular customers.

1) The sampling distribution of X bar

Select one:

a. is not normal because the sample size is too large

b. is not normal because the sample size is too small

c. is normal due to the Chebyshev's Theorem

d. is normal due to the Central Limit Theorem

2) The standard error (SE) of X bar is

Select one:

a. 132

b. 60.8

c. 1.32

d. 9.33

3) What is the probability that a random sample of 200 cellular customers will provide an average(X bar) that is within $25 of the population mean (µ)?

Select one:

a. 6%

b. 3%

c. 97%

d. 99%

4) The probability in the PRECEDING question would _______ if we were to increase the sample size (n) from 200 to 251.

Select one:

a. decrease

b. be zero

c. stays the same

d. increase

5) Suppose we reduce the sample size (n) from 200 to 25. The sampling distribution of X bar will be normal only if

Select one:

a. X is normally distributed

b. X has a left skewed distribution

c. X has a right skewed distribution

d. X has a bi-modal distribution

Answer 1