QUESTION 1

The monthly electrical utility bills of all customers for the Far East Power and Light Company are known to be distributed as a normal distribution with mean equal to $87.00 a month and standard deviation of $36.00. If a statistical sample of n = 100 customers is selected at random, what is the probability that the mean bill for those sampled will exceed $75.00?

	a.	-0.33.
	b.	Approximately 0.63.
	c.	About 1.00.
	d.	3.33.

QUESTION 2

The time between calls to an emergency 911-call center is exponentially distributed with a mean time between calls of 645 seconds. Based on this information, what is the probability that the time between the next two calls is between 200 and 400 seconds?

	a.	Approximately 0.47.
	b.	About 0.199.
	c.	About 0.747.
	d.	About 0.801.

QUESTION 3

The St. Joe Company grows pine trees and the average annual increase in tree diameter is 3.1 inches with a standard deviation of 0.5 inch. A random sample of n = 50 trees is collected. What is the probability of the sample mean being less than 2.9 inches?

	a.	0.4977.
	b.	0.0023.
	c.	0.9977.
	d.	0.9954.

QUESTION 4

Which of the following statements is false?

	a.	Increasing the sample size will always reduce the size of the sampling error when the sample mean is used to estimate the population mean.
	b.	Increasing the sample size will reduce the potential for extreme sampling error.
	c.	Sampling error can occur when the sample mean differs from the population mean due to the fact that the sample was not a perfect reflection of the population.
	d.	There is no way to prevent sampling error short of taking a census of the entire population.

QUESTION 5

Which of the following regression output values is used in computing the variance inflation factors?

	a.	The standard error of the estimate.
	b.	The regression intercept value.
	c.	The F critical value from the F distribution for the appropriate number of degrees of freedom. and the appropriate level of significance.
	d.	The R-squared value.