A new extended-life light bulb has an average life of 750 hours, with a standard
deviation of 50 hours. If the life of these light bulbs approximates a normal distribution,
about what percent of the distribution will be between 600 hours and 900 hours?
A. 95%
B. 68%
C. 34%
D. 99.47%
Consider a right-tailed test (upper tail) and a sample size of 40 at the 95% confidence
level. The value of t is ________.
A. +2.023
B. -2.023
C. -1.685
D. +1.685
The mean score of a college entrance test is 500; the standard deviation is 75. The
scores are normally distributed. What percent of the students scored below 320?
A. About 50.82%
B. About 34.13%
C. About 7.86%
D. About 0.82%
A researcher is studying the effect of 10 different variables on a critical measure of
business performance. In selecting the best set of independent variables to predict the
dependent variable, the stepwise regression technique is used. How are variables
selected for inclusion in the model?
A. Highest increase in the multiple R2
B. Largest p-value
C. Smallest p-value
D. Smallest regression coefficient
If the decision is to reject the null hypothesis of no difference between two population
proportions at the 5% level of significance, what are the alternative hypothesis and
rejection region?
A. H1: π1 ≠π2; z > +1.645 and z < -1.645
B. H1: π1 ≠π2; z > +1.960 and z < -1.960
C. H1: π1 > π2; z < -1.645
D. H1: π1 > π2; z < -1.960
To apply the large-sample procedure for the sign test, the sample size should be at least
_____.
A. 2
B. 8
C. 100
D. 10
The center of a normal probability distribution is ________.
A. the same as the standard deviation or the distribution
B. never negative
C. the mean of the distribution
D. always equal to zero
The results of a mathematics placement exam at two different campuses of Mercy
College follow:
What is the alternative hypothesis if we want to test the hypothesis that the mean score
on Campus 1 is higher than on Campus 2?
A. H1: 1 = 0
B. H1: 2 = 0
C. H1: 1 > 2
D. H1: 1 ≤ 2
A company is studying the number of monthly absences among its 125 employees. The
following probability distribution shows the likelihood that people were absent 0, 1, 2,
3, 4, or 5 days last month.
What is the variance of the number of days absent?
A. 1.1616
B. 1.41
C. 5.00
D. 55.52
A sales manager for an advertising agency believes that there is a relationship between
the number of contacts that a salesperson makes and the amount of sales dollars earned.
What is the dependent variable?
A. Salesperson
B. Number of contacts
C. Amount of sales dollars
D. Sales manager
Random samples of four items are selected from a manufacturing process at regular
intervals and a certain quality characteristic is measured. After 25 samples, ΣX =
15,350 and ΣR = 411.4. To construct a range chart, what is the lower control limit
(LCL) for the range?
A. 602.004
B. 411.400
C. 625.666
D. 0.00
In the following table,
A. There are 16 observations.
B. There are four observations in the second class.
C. There are ten observations less than thirty.
D. There are ten observations greater than thirty.
It has been hypothesized that overall academic success for college freshmen as
measured by grade point average (GPA) is a function of IQ scores, X1, hours spent
studying each week, X2, and one’s high school average, X3. Suppose the regression
equation is . The multiple standard error is 6.313 and R2 = 0.826.
Which independent variable has the smallest effect on GPA?
Which of the following is a characteristic of the normal probability distribution?
A. It’s positively skewed.
B. It’s bell-shaped.
C. It’s asymmetrical.
D. It’s rectangular.
If Spearman’s rank correlation statistic is -0.91 with a sample size of 10, what is the test
statistic value to test the hypothesis that the rank correlation coefficient is zero?
A. -6.2080
B. 6.2080
C. 1.960
D. 2.262
An automatic machine inserts mixed vegetables into a plastic bag. Past experience
revealed that some packages were underweight and some were overweight, but most of
them had satisfactory weight.
What is the probability of selecting three packages that are overweight?
A. 0.0000156
B. 0.0004219
C. 0.0000001
D. 0.075
A dot plot is best applied for a data set with __________.
A. 1,000 observations
B. 50 observations
C. More than one variable
D. One mode
A student was studying the political party preferences of a university’s student
population. The survey instrument asked students to identify their political
preference’”for example, Democrat, Republican, Libertarian, or another party. The best
way to illustrate the relative frequency distribution is a __________.
A. Bar chart
B. Pie chart
C. Histogram
D. Frequency polygon
In the equation, Ŷ = a + bX, what is Ŷ?
A. It is the slope of the line.
B. It is the Y intercept.
C. It is the predicted value of Y, given a specific X value.
D. It is the value of Y when X = 0.
A person is trying to decide if they should buy a lottery ticket. The ticket costs $2.00. If
the ticket is a winner, the prize would be $1,000. Knowing that winning $1,000 is not a
certain outcome (state of nature), the person finds that the probability of winning is
0.001. Based on this information, the following payoff table can be constructed:
What is the decision using a maximin approach?
A. Buy
B. Don’t buy
C. Lose
D. Win
A statistics professor receives an average of five e-mail messages per day from
students. Assume the number of messages approximates a Poisson distribution. What is
the probability that on a randomly selected day she will have five messages?
A. 0.0067
B. 0.8750
C. 0.1755
D. 1.0000
A sales manager for an advertising agency believes that there is a relationship between
the number of contacts that a salesperson makes and the amount of sales dollars earned.
A regression analysis shows the following results:
What is the decision regarding the hypothesis if the slope equals zero?
A. Fail to reject the null hypothesis.
B. Fail to reject the alternative hypothesis.
C. Reject the null hypothesis.
D. Reject the alternative hypothesis.
Affirmative action commitments by many organizations have led to an increase in the
number of women in executive positions. Satellite Office Systems has vacancies for
two executives that it will fill from among four women and six men.
What is the probability that no woman is selected?
A. 1/5
B. 1/3
C. 2/15
D. 8/15
The marketing department of a nationally known cereal maker plans to conduct a
national survey to find out whether or not consumers of flake cereals can distinguish
one of their favorite flake cereals. To test the questionnaire and procedure to be used,
eight persons were asked to cooperate in an experiment. Five very small bowls of flake
cereals were placed in front of a person. The bowls were labeled A, B, C, D and E. The
person was informed that only one bowl contained his or her favorite flake cereal.
Suppose that the eight persons in the experiment were unable to identify their favorite
cereal and just guessed which bowl it was in. What is the probability that none of the
eight guessed correctly?
A. 0.168
B. 0.009
C. 0.788
D. 0.125
In the Kruskal-Wallis test for the following data, what is the sum of the ranks for
Sample 3?
A. 57
B. 80
C. 4
D. 210
A local health care company wants to estimate the mean weekly elder day-care cost. A
sample of 10 facilities shows a mean of $250 per week, with a standard deviation of
$25. What is the 90% confidence interval for the population mean?
The American Auto Association reports that the mean price per gallon of regular
gasoline is $3.10, with a population standard deviation of $0.20. Assume a random
sample of 16 gasoline stations is selected and their mean cost for regular gasoline is
computed. What is the standard error of the mean in this experiment?
A bottle cap manufacturer with four machines and six operators wants to see if variation
in production is due to the machines and/or the operators. The ANOVA table follows.
What is the mean square for machines?
A data set has 100 observations. In the data, a quantitative variable’s highest value is
117 and its lowest value is 47. What is the minimum class interval that you would
recommend?
For any probability distribution, the standard deviation is the ______________.
A local grocery store wants to estimate the mean daily number of gallons of milk sold
to customers. Assume the number of gallons sold follows the normal distribution, with a
population standard deviation of 5.10 gallons. A random sample of 60 days shows that
the mean daily number of gallons sold is 10.00. What is the point estimate of the
population mean?