Exam: 250714RR - Inferences and Linear Regression
When you have completed your exam and reviewed your answers, click Submit Exam. Answers will not be recorded until you hit Submit Exam. If you need to exit before completing the exam, click Cancel Exam.
Questions 1 to 20: Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that you have seen the entire question and all the answers before choosing an answer.
1. Given the significance level 0.05, the F-value for the degrees of freedom, df = (3,7) is
A. 6.16.
B. 4.35.
C. 8.89.
D. 4.12.
2. In a hypothesis test for the population variance, the alternate hypothesis is the population variance does not equal 17.0. The significance level to be used is 0.05 and the sample size to be taken is 25. The table value(s) to use from the chi-square distribution is/are
A. 40.647.
B. 39.364.
C. 12.401 and 39.364.
D. 13.120 and 40.647.
3. In using the ANOVA models, the assumptions made about the data are
A. the samples are independent.
B. the population variances are equal.
C. the population distributions are normal.
D. all 3 assumptions made here about the data.
4. A left-tail area in the chi-square distribution equals 0.95. For df = 10, the table value equals
A. 20.483.
B. 18.307.
C. 3.940.
D. 15.987.
5. A balanced experiment requires that
A. the number of treatments equals the number of samples.
B. at least two treatment groups be used.
C. an equal number of persons or test units receives each treatment.
D. at least one sample equal size is 30.
6. The F-statistic in a one-way ANOVA represents the variation
A. within the treatments minus the variation between the treatments.
B. between the treatments divided by the variation within the treatments.
C. between the treatments plus the variation within the treatments.
D. within the treatments divided by the variation between the treatments.
7. A random sample of males and females involved in rear-end accidents results in the following Minitab
summary:
What is the value of the test statistic (Z score)?
N MEAN MEDIAN TRMEAN STDEV SEMEAN
FEMALES 33 23.91 20.00 23.38 9.77 1.70
MALES 38 28.87 28.50 28.44 9.67 1.57
A. −2.14
B. 1.64
C. −4.96
D. 2.32
8. A chi-square test for independence with 8 degrees of freedom results in a test statistic of 18.21. Using the chi-square table, the most accurate statement that can be made about the p-value for this test is that
A. 0.05 > p-value > 0.025.
B. p-value < 0.01.
C. 0.025 > p-value > 0.01.
D. 0.10 > p-value > 0.05.
9. A random sample of males and females involved in rear-end accidents results in the following Minitab
summary:
What is the standard error of the statistic between the two means?
N MEAN MEDIAN TRMEAN STDEV SEMEAN
FEMALES 33 23.91 20.00 23.38 9.77 1.70
MALES 38 28.87 28.50 28.44 9.67 1.57
A. 1.635
B. 0.897
C. 4.96
D. 2.314
10. In testing the difference between two population means using two independent samples, the sampling distribution of the sample mean difference x̄1 − x̄2 is normal if the
A. sizes are both greater than 30.
B. populations are normal.
C. populations are nonnormal and the sample sizes are large.
D. population sizes are both greater than 30.
11. The object on which the response and factors are observed is called
A. factor level.
B. treatments.
C. factors.
D. experimental unit.
12. Given the significance level 0.025, the F-value for the degrees of freedom, df = (7,3) is
A. 14.62.
B. 8.45.
C. 27.67.
D. 5.89.
13. An indication of no linear relationship between two variables would be a coefficient of
A. determination equal to 1.
B. determination equal to −1.
C. correlation of 0.
D. correlation equal to −1.
14. A "best-fit" mathematical equation for the values of two variables, x and y, is called
A. correlation analysis.
B. errors of prediction.
C. regression analysis.
D. scatter diagram.
15. Another name for the residual term in a regression equation is
A. residual analysis.
B. homoscedasticity.
C. random error.
D. pooled variances.
16. In testing a population variance or constructing a confidence interval for the population variance, an essential assumption is that
A. the population is normally distributed.
B. expected frequencies equal or exceed 5.
C. sample size exceeds 30.
D. the population is uniformly distributed.
17. What is the slope of the line that passes through the points (−5, −8) and (3,8)?
A. ½
B. −½
End of exam
C. −2
D. 2
18. Consider the following data values of variables x and y.
Find the least squares regression line.
x 4 2 6 4 3
y 5 3 7 6 5
A. −1.045 + 0.932x
B. 21.206 + 1.073x
C. 1.122 + 1.073x
D. 1.659 + 0.932x
19. A regression analysis between sales (in $1000) and advertising (in $) resulted in the following least squares line: yˆ = 80,000 + 5x. This implies that an increase of _______ in advertising is expected to result in an increase of _______ in sales.
A. $1, $5
B. $1, $5,000
C. $1, $80,005
D. $5, $5,000
20. Lily Energy Systems manufacturer's wood-burning heaters and fireplace inserts. One of its systems has an electric blower, which is thermostatically controlled. The blower is designed to automatically turn on when the temperature in the stove reaches 125°F and turn off at 85°F. Complaints from customers indicate that the thermostat control is not working properly. The company feels that the thermostat is acceptable if the variance in the cutoff temperature is less than or equal to 175. The company takes a sample of 24
thermostats and finds that the variance equals 289. The calculated chi-square test statistic and the table value for a 0.05 significance level are
A. 35.172, 38.99.
B. 38.076, 38.99.
C. 37.983, 35.172.
D. 37.983, 38.076.
No comments:
Post a Comment