A random sample of nine telephone calls in an office provided the following
information.
a. Determine the point estimate for the average duration of all calls.
b. What is the point estimate for the standard deviation of the population?
c. What is the point estimate for the proportion of all calls that were long distance?
Exhibit 6-3
The weight of football players is normally distributed with a mean of 200 pounds and a
standard deviation of 25 pounds.
Refer to Exhibit 6-3. What is the minimum weight of the middle 95% of the players?
a. 196
b. 151
c. 249
d. None of the alternative answers is correct.
Exhibit 15-3
In a regression model involving 30 observations, the following estimated regression
equation was obtained:
= 17 + 4x1 – 3x2 + 8x3 + 8x4
For this model SSR = 700 and SSE = 100.
Refer to Exhibit 15-3. The computed F statistic for testing the significance of the above
model is
a. 43.75
b. 0.875
c. 50.19
d. 7.00
Exhibit 6-6
The life expectancy of a particular brand of tire is normally distributed with a mean of
40,000 and a standard deviation of 5,000 miles.
Refer to Exhibit 6-6. What percentage of tires will have a life of 34,000 to 46,000
miles?
a. 38.49%
b. 76.98%
c. 50%
d. None of the alternative answers is correct.
The null hypothesis in the Durbin-Watson test is always that there is
a. positive autocorrelation
b. negative autocorrelation
c. either positive or negative autocorrelation
d. no autocorrelation
A theorem that allows us to use the normal probability distribution to approximate the
sampling distribution of sample means and sample proportions whenever the sample
size is large is known as the
a. approximation theorem
b. normal probability theorem
c. central limit theorem
d. central normality theorem
The marketing department of a company has designed three different boxes for its
product. It wants to determine which box will produce the largest amount of sales. Each
box will be test marketed in five different stores for a period of a month. Below you are
given the information on sales.
a. State the null and alternative hypotheses.
b. Construct an ANOVA table.
c. What conclusion do you draw?
d. Use Fisher’s LSD procedure and determine which mean (if any) is different from the
others. Let = 0.01.
A term that means the same as the term “variable” in an ANOVA procedure is
a. factor
b. treatment
c. replication
d. variance within
The probability assigned to each experimental outcome must be
a. any value larger than zero
b. smaller than zero
c. one
d. between zero and one
The function used to compute the probability of x successes in n trials, when the trials
are dependent, is the
a. binomial probability function
b. Poisson probability function
c. hypergeometric probability function
d. exponential probability function
The following is part of the results of a regression analysis involving sales (y in
millions of dollars), advertising expenditures (x1 in thousands of dollars), and number
of sales people (x2) for a corporation:
a. At = 0.05 level of significance, test to determine if the model is significant. That is,
determine if there exists a significant relationship between the independent variables
and the dependent variable.
b. Determine the multiple coefficient of determination.
c. Determine the adjusted multiple coefficient of determination.
d. What has been the sample size for this regression analysis?
SSE can never be
a. larger than SST
b. smaller than SST
c. equal to 1
d. equal to zero
In a multiple regression analysis involving 12 independent variables and 166
observations, SSR = 878 and SSE = 122. The coefficient of determination is
a. 0.1389
b. 0.1220
c. 0.878
d. 0.7317
Telephone calls arrive at the Global Airline reservation office in Louisville according to
a Poisson distribution with a mean of 1.2 calls per minute.
a. What is the probability of receiving exactly one call during a one-minute interval?
b. What is the probability of receiving at most 2 calls during a one-minute interval?
c. What is the probability of receiving at least two calls during a one-minute interval?
d. What is the probability of receiving exactly 4 calls during a five-minute interval?
e. What is the probability that at most 2 minutes elapse between one call and the next?
The “Top Three” at a racetrack consists of picking the correct order of the first three
horses in a race. If there are 10 horses in a particular race, how many “Top Three”
outcomes are there?
a. 302,400
b. 720
c. 1,814,400
d. 10
Exhibit 16-4
In a laboratory experiment, data were gathered on the life span (y in months) of 33 rats,
units of daily protein intake (x1), and whether or not agent x2 (a proposed life extending
agent) was added to the rats diet (x2 = 0 if agent x2 was not added, and x2 = 1 if agent
was added.) From the results of the experiment, the following regression model was
developed.
= 36 + 0.8x1 – 1.7x2
Also provided are SSR = 60 and SST = 180.
Refer to Exhibit 16-4. The test statistic for testing the significance of the model is
a. 0.50
b. 5.00
c. 0.25
d. 0.33
If P(A) = .6, P(B) = .3, and P(A ‡ B) = .2, then P(B|A) =
a. .33
b. .5
c. .67
d. .9
The level of significance is the
a. maximum allowable probability of Type II error
b. maximum allowable probability of Type I error
c. same as the confidence coefficient
d. same as the p-value
The mean of the sample
a. is always larger than the mean of the population from which the sample was taken
b. is always smaller than the mean of the population from which the sample was taken
c. can never be zero
d. None of the other answers are correct.
For an F distribution, the number of degrees of freedom for the numerator
a. must be larger than the number of degrees for the denominator
b. must be smaller than the number of degrees of freedom for the denominator
c. must be equal to the number of degrees of freedom for the denominator
d. can be larger, smaller, or equal to the number of degrees of freedom for the
denominator
The following are partial results of a regression analysis involving sales (y in millions
of dollars), advertising expenditures (x1 in thousands of dollars), and number of
salespeople (x2) for a corporation. The regression was performed on a sample of 10
observations.
The fact that the sampling distribution of the sample mean can be approximated by a
normal probability distribution whenever the sample size is large is based on the
a. central limit theorem
b. fact that there are tables of areas for the normal distribution
c. assumption that the population has a normal distribution
d. All of these answers are correct.