BSTAT 5325 – Exam 1 Version White, Summer, 2010 - Printed Name___________________________
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least a zero on this test and could include expulsion from the university and that all the work on this exam is
mine.
Directions
1. Do not open exam until told.
2. Set all pagers and cell phones to silent and place on floor or backpack
3. When finished place all material inside your exam and place on desk in front.
4. Assume  = 0.05 and confidence of 95% unless told otherwise.
5. Cell phones (and any other internet enabled device) cannot be used as calculators.
6. Bubble in your last name, skip a space and then your first name
I have read and I understand all the directions above.
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1. What testing the equality of 5 population means, would be wrong with using an F-test value = -0.935?
a. Ratios must be larger than two.
b. Nothing is wrong with this value.
c. The F cannot be negative
d. You should be using a t-test not an F test
2. If you find the F-test value to be smaller than the F-table value, you can
a. conclude that all the sample means have the same value.
b. conclude that all the population means have the same value.
c. not conclude that the population means differ
d. conclude that the population means equal the sample means.
3. In a random sample of 5000 city residents, you find 10 that have finished a MBA. Of the 5000, 40% are
women. Of the women 3 have a MBA. What is wrong with using the chi-square test to see if the gender and
obtainment of a MBA are related? (If you have not studied this well, it might seem tricky.)
a. not a random sample
b. should have used an F test instead.
c. the sample size is too small.
d. not enough information is given to complete the table
4. In both the chi-square test of independence and analysis of variance, the factor is qualitative. However in
the chi-square test the response is __________ while in analysis of variance the response is __________
The answers below are in the same order as the blank positions in the question.
a. qualitative; quantitative
b. greater than 30; smaller than 30
c. a non-random sample; a random sample
d. quantitative; qualitative
5. As the sample size gets larger, the
a. the distribution of the original population of data changes to a normal distribution
b. the font size changes.
c. the standard error of the sample mean gets larger and larger
d. the distribution of sample means approaches a normal distribution.
6. After determining that at least one of the population means differ from the others, what would be obvious
next question?
a. Do the populations have a standard binomial distribution?
b. Uhhh, why exactly did I want to do this? (Hint; good question, but wrong answer to this problem)
c. Which means differ and by how much?
d. Are the population means the same?
7. If a normally distributed population has a mean of 45 and a standard deviation of 2, then what percent of
the population will fall between 41 and 45? Approximately ….
a. 2.5%
b. 47.5%
c. 68%
d. none of the other answers are correct.
8. All other assumptions being met, if you are trying to estimate the population mean and the population
standard deviation is not known, what table value would you use?
a. t-table with n-1 degrees of freedom
b. chi-square table with n-1 degrees of freedom
c. F table with no degrees of freedom
d. z-table
9. The chi-square test for a contingency table can be used to test either independence or ….
a. estimate a population distribution
b. equal proportions
c. wash your car (Hint: do I really need a hint here?)
d. determine differences in sample means
10. What is the symbol for the standard deviation of a sample?
a. 
b. 
c. s
d. 
11. Decreasing the confidence level of a confidence interval from say 99% to 95%
a. increases the sample mean
b. decreases the population mean
c. decreases the margin of error
d. decreases the standard error
12. Which of the following is not an appropriate alternative hypothesis, H1:……?
a. not all population means are equal
b. the two qualitative variables are related
c. x ≠ 20
d. 
13. If  is known, what would you have to do to shrink the standard error of a sample mean to half its
current value?
a. triple the sample size
b. quadruple the sample size
c. double the population standard deviation
d. double the sample size.
14. Suppose you find that the variability of the sample means is 400 times what you expected the variation it
should have been if the population means had been equal. Which of the equations below represent this?
a. F = 400
b. 2 = 400
c. t = 400
d. 2 = 400.
15. A list of all possible sample means along with their probabilities is called ….
a. the standard error of the mean
b. the margin of error of the mean
c. George
d. the sampling distribution of the mean
16. You wish to show that the population mean is lower than 25. From a random sample of 15 companies
you calculate a test value of 1.45. What would be the rejection region? Reject Ho if
a. t > 1.761
b. t > 2.145 or t < -2.145
c. t < -1.761
d. none of the other answers are correct.
17. What is the confidence interval for the population mean if you are given that the sample mean is 17.2,
the population standard deviation is 12 and the sample size is 144?
a. (15.22 to 19.18)
b. none of the other answers are correct.
c. (16.2 to 18.2)
d. (15.24 to 19.16)
18. Suppose in credit scoring, the null hypothesis is that the person should not get the loan. What would be
the consequence of a type I error to the bank?
a. They lose money due to a default on the loan payment by the customer.
b. Giving them the loan.
c. They lose the profit to be gained from the loan.
d. It is the five percent margin of error.
19. What would cause you to support that the population mean is less than 20? Assume the population is
normal but sigma is not known
a. t test values either larger than a positive t-table value or less than a negative t-table value
b. F test values larger than an F table value
c. t test values larger than some positive t-table value
d. t test values less than some negative t-table value
20. As we have used it, a hypothesis test asks
a. for an estimate of the value of a population parameter.
b. you to draw a histogram and determine the number of people who will be in a random sample.
c. for an estimate of the value of a sample statistic.
d. whether you can support that a parameter takes on a specific set of values.
21. One of the following is a basis of both our confidence intervals and hypothesis tests. Which one?
a. a random sample
b. a sample standard deviation
c. a sample mean
d. a t-table value
22. You have a random sample of 8 objects from each of 5 populations. What table value would you use to
show that at least two population means differ?
a. Chi-square(28)
b. t(7)
c. q(4, 35)
d. F(4, 35)
23. You want to determine if sleep affects the passing of an exam and have divided thirty students into three
groups of ten. The first group is required to stay up all night studying for the exam. The second group does
not study at all. The third group studies the previous day and gets eight hours of sleep. If you record only
whether they pass or fail the exam what procedure would you use?
a. count the number of passing grades. Whichever is the highest is the best.
b. the F-test of equal means
c. the t-test
d. the chi-square test of equal proportions
24. Which of the following allows you to make cause-effect statements?
a. a convenience sample
b. an experiment
c. a survey
d. the sample size
25. You have three random samples of 4 each. If you have an ANOVA test statistic value of 10.34, would
you reject equal means? Why or why not?
a. Yes because the F is larger than the table value.
b. Yes because the t-value is too close to zero.
c. No because the F value is too small.
d. No and for no particular reason.
26. Suppose you are making a new absorbent paper towel and wish to compare it to the two leading brands.
You sample 15 sheets of paper from each of the towels and measure how much water each can absorb. In
this case what would the meaning of the equal variance assumption of analysis of variance?
a. The amount of water absorbed is normally distributed for each of the brands.
b. The variation in Y observed in the sample must be the same for all brands .
c. The population variation in the amount of water absorbed is the same for each of the brands.
d. The sample sizes are all the same.
27. What is the variance of the following population of numbers? 4, 1, 3, 4
a. none of the other answers are correct
b. 1.5
c. 2
d. 0
28. What is the key concept of this course so far (that I have repeatedly stated in class)?
a. Statistics will always give you the correct answer due to its mathematical basis
b. When in doubt, hire a statistician (thank you but choose another answer)
c. Sample statistics almost never equal to the population parameter
d. Of all the parameters covered, you only need to estimate the mean.
29. In the notes, I mentioned that non-response (someone not responding) is a particular problem with …
a. random samples
b. randomized block designs
c. surveys
d. contingency table
30. What is another name for the largest error you would expect when trying to estimate the population
mean?
a. George
b. the standard error
c. the t-table value
d. the margin of error
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