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A sample of 21 elements is selected to estimate a 90% confidence interval for the
variance of the population. The chi-square value(s) to be used for this interval
estimation is (are)
a. -1.96 and 1.96
b. 12.443
c. 10.851 and 31.410
d. 12.443 and 28.412
A market study taken at a local sporting goods store showed that of 20 people
questioned, 6 owned tents, 10 owned sleeping bags, 8 owned camping stoves, 4 owned
both tents and camping stoves, and 4 owned both sleeping bags and camping stoves.
Let Event A = owns a tent, Event B = owns a sleeping bag, Event C = owns a camping
stove, and Sample Space = 20 people questioned.
a. Find P(A), P(B), P(C), P(A C), P(B C).
b. Are the events A and C mutually exclusive? Explain briefly.
c. Are the events B and C independent events? Explain briefly.
d. If a person questioned owns a tent, what is the probability he also owns a camping
stove?
e. If two people questioned own a tent, a sleeping bag, and a camping stove, how many
own only a camping stove?
f. Is it possible for 3 people to own both a tent and a sleeping bag, but not a camping
stove?
Temperature is an example of
a. a categorical variable
b. a quantitative variable
c. either a quantitative or categorical variable
d. neither a quantitative nor categorical variable
The following regression model
y = 0 + 1x1 + 2x2 +
is known as
a. first-order model with one predictor variable
b. second-order model with two predictor variables
c. second-order model with one predictor variable
d. None of these alternatives is correct.
Monthly total production costs and the number of units produced at a local company
over a period of 10 months are shown below.
Use Excel's Regression Tool to estimate a second-order model of the form
A term used to describe the case when the independent variables in a multiple
regression model are correlated is
a. regression
b. correlation
c. multicollinearity
d. None of the alternative answers are correct.
The population variance can never be
a. zero
b. larger than the standard deviation
c. negative
d. all of these are correct
The interquartile range is
a. the 50th percentile
b. another name for the variance
c. the difference between the largest and smallest values
d. the difference between the third quartile and the first quartile
The following information gives the number of days absent from work for a population
of 5 workers at a small factory.
a. Find the mean and the standard deviation for the population.
b. Samples of size 2 will be drawn from the population. Use the answers in part a to
calculate the expected value and the standard deviation of the sampling distribution of
the sample mean.
c. Find all the samples of 2 workers that can be extracted from this population. Choose
the samples without replacement.
d. Compute the sample mean for each of the samples in Part c.
e. Graph the sample means with the values of on the horizontal axis and the
corresponding relative frequency on the vertical axis.
The proportion of the variation in the dependent variable y that is explained by the
estimated regression equation is measured by the
a. correlation coefficient
b. standard error of the estimate
c. coefficient of determination
d. confidence interval estimate
In a local university, 10% of the students live in the dormitories. A random sample of
100 students is selected for a particular study.
The sampling distribution used when making inferences about a single population's
variance is
a. an F distribution
b. a t distribution
c. a chi-square distribution
d. a normal distribution
Sandy's Pet Center grooms large and small dogs. It takes Sandy 40 minutes to groom a
small dog and 70 minutes to groom a large dog. Large dogs account for 20% of Sandy's
business. Sandy has 5 appointments tomorrow.
a. What is the probability that all 5 appointments tomorrow are for small dogs?
b. What is the probability that two of the appointments tomorrow are for large dogs?
c. What is the expected amount of time to finish all five dogs tomorrow?
Exhibit 16-2
In a regression model involving 30 observations, the following estimated regression
equation was obtained.
= 170 + 34x1 - 3x2 + 8x3 + 58x4 + 3x5
For this model, SSR = 1,740 and SST = 2,000.
Refer to Exhibit 16-2. The degrees of freedom associated with SSE are
a. 24
b. 6
c. 19
d. 5
A sampling unit
a. must have one element
b. may include several elements
c. cannot include more than one element
d. None of these alternatives is correct.
Exhibit 15-7
A regression model involving 4 independent variables and a sample of 15 periods
resulted in the following sum of squares.
SSR = 165
SSE = 60
Refer to Exhibit 15-7. If we want to test for the significance of the model at 95%
confidence, the critical F value (from the table) is
a. 3.06
b. 3.48
c. 3.34
d. 3.11
In computing descriptive statistics from grouped data,
a. data values are treated as if they occur at the midpoint of a class
b. the grouped data result is more accurate than the ungrouped result
c. the grouped data computations are used only when a population is being analyzed
d. All of these answers are correct.
A regression model involved 18 independent variables and 200 observations. The
critical value of t for testing the significance of each of the independent variable's
coefficients will have
a. 18 degrees of freedom
b. 200 degrees of freedom
c. 199 degrees of freedom
d. 181 degrees of freedom
Z is a standard normal random variable. What is the value of z if the area to the right of
z is 0.9803?
a. -2.06
b. 0.4803
c. 0.0997
d. 3.06
