51. Which of the following observed on a control chart suggests a process that is not in
control?
a. Points follow a smooth pattern from the lower control limit to the upper control limit
b. The number of points above and below the center line is about the same
c. Points fall randomly above and below the center line
d. No points are outside the control limits
The process mean and standard deviation can be estimated by using samples that are
selected from the process when
a. it has only assignable-cause variation
b. its output is uniformly distributed
c. it is assumed to be operating in control
d. it is operating at peak capacity
Exhibit 15-6
Below you are given a partial Excel output based on a sample of 16 observations.
Refer to Exhibit 15-6. The F value obtained from the table used to test if there is a
relationship among the variables at the 5% level equals
a. 3.41
b. 3.63
c. 3.81
d. 19.41
In a stem-and-leaf display,
a. a single digit is used to define each stem, and a single digit is used to define each leaf
b. a single digit is used to define each stem, and one or more digits are used to define
each leaf
c. one or more digits are used to define each stem, and a single digit is used to define
each leaf
d. one or more digits are used to define each stem, and one or more digits are used to
define each leaf
A regression model relating units sold (y), price (x1), and whether or not promotion was
used (x2 = 1 if promotion was used and 0 if it was not) resulted in the following model.
= 120 – 0.03x1 + 0.7x2
and the following information is provided.
n = 15 Sb1 = .01 Sb2 = 0.1
Arithmetic operations are inappropriate for
a. categorical data
b. quantitative data
c. both categorical and quantitative data
d. large data sets
A student believes that the average grade on the final examination in statistics is at least
85. She plans on taking a sample to test her belief. The correct set of hypotheses is
a. H0: 85 Ha: 85
b. H0: 85 Ha: 85
c. H0: 85 Ha: 85
d. None of the other answers are correct.
The sampling distribution of the ratio of independent sample variances extracted from
two normal populations with equal variances is the
a. chi-square distribution
b. normal distribution
c. Z distribution
d. t distribution
Exhibit 7-1
The following data was collected from a simple random sample from a process (an
infinite population).
Refer to Exhibit 7-1. The point estimate of the population mean
a. is 5
b. is 14
c. is 4
d. cannot be determined because the population is infinite
Which of the following is a characteristic of a binomial experiment?
a. at least 2 outcomes are possible
b. the probability of success changes from trial to trial
c. the trials are independent
d. All of these answers are correct.
In order to estimate the difference between the yearly incomes of marketing managers
in the East and West of the United States, the following information was gathered.
Exhibit 13-3
To test whether or not there is a difference between treatments A, B, and C, a sample of
12 observations has been randomly assigned to the 3 treatments. You are given the
results below.
Refer to Exhibit 13-3. The mean square within treatments (MSE) equals
a. 1.872
b. 5.86
c. 34
d. 36
Exhibit 16-1
In a regression analysis involving 25 observations, the following estimated regression
equation was developed.
= 10 – 18x1 + 3x2 + 14x3
Also, the following standard errors and the sum of squares were obtained.
Sb1 = 3 Sb2 = 6 Sb3 = 7
SST = 4,800 SSE = 1,296
Refer to Exhibit 16-1. The coefficient of x2
a. is significant
b. is not significant
c. cannot be tested, because not enough information is provided
d. None of these alternatives is correct.
Exhibit 11-6
We want to test the hypothesis that the population variances are equal.
Refer to Exhibit 11-6. The test statistic for this problem equals
a. .67
b. .84
c. 1.19
d. 1.50
The target population and the sampled population
a. are always the same
b. are not always the same
c. must be the same for the results to be accurate
d. None of these alternatives is correct.
The reliability of two types of machines used in the same manufacturing process is to
be tested. The first machine failed to operate correctly in 90 out of 300 trials while the
second type failed to operate correctly in 50 out of 250 trials.
a. Give a point estimate for the difference between the population proportions of these
machines.
b. Calculate the pooled estimate of the population proportion.
c. Carry out a hypothesis test to check whether there is a statistically significant
difference in the reliability for the two types of machines using a .10 level of
significance.
If a hypothesis is not rejected at a 5% level of significance, it will
a. also not be rejected at the 1% level
b. always be rejected at the 1% level
c. sometimes be rejected at the 1% level
d. Not enough information is given to answer this question.