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m102910 | What percent of undergraduate enrollment in coed colleges and universities in the United States is male? A random sample of 50 such institutions give the following data (Source USA Today allege Guide). Percent Males Enrolled in Coed Universities and Colleges
Use five classes. |
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m102911 | What type of graph for frequency data should you construct when distributing each of the following? Note that there may be more than one right answer.
(a) The number of students falling into an A, B, C, D, or F grade range
(b) The number of men and women suffering from depression
(c) The number of autistic children showing improvement following one of three behavioral therapies
(d) The time it takes a sample of college students to complete some memory task |
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m102912 | When a balanced coin is tossed four times, 16 equally likely outcomes are possible, as shown in the following table.
Let
A = event the first toss is heads,
B = event the second toss is tails, and
C = event the last two tosses are heads.
Apply the definition of independence for three events stated in Exercise 4.204 to show that A, B, and C are independent events.
In E 4.204
P(A & B) = P(A) · P(B),
P(A & C) = P(A) · P(C),
P(B & C) = P(B) · P(C), and
P(A & B & C) = P(A) · P(B) · P(C). |
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m102913 | When a balanced dime is tossed three times, eight equally likely outcomes are possible:
HHH ...... HTH ......THH ......TTH
HHT ....... HTT ......THT .......TTT
Let
A = event the first toss is heads,
B = event the third toss is tails, and
C = event the total number of heads is 1.
a. Compute P(A), P(B), and P(C).
b. Compute P(B | A).
c. Are A and B independent events? Explain your answer.
d. Compute P(C | A).
e. Are A and C independent events? Explain your answer. |
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m102914 | When does restriction of range limit the interpretation of a significant correlation? |
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m102915 | When is it appropriate to compute the one-way within-subjects ANOVA? |
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m102916 | When responses are not obtained from some of the individuals in the sample because either those individuals cannot be reached or refuse to participate, we have nonresponse bias.
a. Discuss some of the dangers of nonresponse.
b. Many sample surveys that are reported in the media have response rates as low as 10%. Explain the consequences of such low response rates in trying to generalize the results to the entire population. |
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m102917 | When testing m or the difference of means µ1 - µ2 from independent populations, how do we decide whether to use the standard normal distribution or a Student s t distribution? |
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m102918 | When the behavior of the interviewer or respondent results in inaccurate responses we have response bias.
a. Explain why a survey question "Do you smoke marijuana" might result in response bias?
b. Provide some additional survey situations that might be conducive to response bias.
c. Provide some additional factors that might lead to response bias. |
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m102919 | When two balanced dice are rolled, 36 equally likely outcomes are possible, as depicted in Fig. 4.1 on page 159. Let
A = event the red die comes up even,
B = event the black die comes up odd,
C = event the sum of the dice is 10, and
D = event the sum of the dice is even.
a. Compute P(A), P(B), P(C), and P(D).
b. Compute P(B | A).
c. Are events A and B independent? Why or why not?
d. Compute P(C | A).
e. Are events A and C independent? Why or why not?
f. Compute P(D | A).
g. Are events A and D independent? Why or why not? |
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m102920 | When two balanced dice are rolled, 36 equally likely outcomes are possible, as illustrated in Fig. 4.1 on page 159. Let
In Fig 4.1
A = event the red die comes up even,
B = event the black die comes up even,
C = event the sum of the dice is even,
D = event the red die comes up 1, 2, or 3,
E = event the red die comes up 3, 4, or 5, and
F = event the sum of the dice is 5.
Apply the definition of independence for three events stated in Exercise 4.204 to solve each problem.
a. Are A, B, and C independent events?
b. Show that P(D & E & F) = P(D) · P(E) · P(F) but that D, E, and F are not independent events. |
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m102921 | When two balanced dice are rolled, 36 equally likely outcomes are possible, as depicted in Fig. 4.1 on page 159. Let Y denote the sum of the dice.
a. What are the possible values of the random variable Y?
b. Use random-variable notation to represent the event that the sum of the dice is 7.
c. Find P(Y = 7).
d. Find the probability distribution of Y. Leave your probabilities in fraction form.
e. Construct a probability histogram for Y. |
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m102922 | When you use the standard deviation as a measure of variation, what is the reference point? |
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m102923 | Where are the deer? Random samples of square-kilometer plots were taken in different ecological locations of Mesa Verde National Park. The deer counts per square kilometer were recorded and are shown in the following table (Source: The Mule Deer of Mesa Verde National Park, edited by G. W. Mierau and J. L. Schmidt, Mesa Verde Museum Association).
Shall we reject or accept the claim that there is no difference in the mean number of deer per square kilometer in these different ecological locations? Use a 5% level of significance.
In the problem, please provide the following information.
(a) What is the level of significance? State the null and alternate hypotheses.
(b) Find SSTOT, SSBET, and SSW and check that SSTOT - SSBET + SSW. Find d.f.BET, d.f.W, MSBET, and MSW. Find the value of the sample test statistic F (F ratio).
What are the degrees of freedom?
(c) Find (or estimate) the P-value of the sample test statistic.
(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis?
(e) Interpret your conclusion in the context of the application.
(f) Make a summary table for your ANOVA test. |
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m102924 | Which is the predictor variable (X) and which is the criterion variable (Y) for each of the following examples?
(a) A researcher tests whether the size of an audience can predict the number of mistakes a student makes during a classroom presentation.
(b) A social psychologist tests whether the size of a toy in cereal boxes can predict preferences for that cereal.
(c) A military officer tests whether the duration of an overseas tour can predict the morale among troops overseas. |
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m102925 | Which of the following sampling procedures involve the use of probability sampling?
a. A college student is hired to interview a sample of voters in her town. She stays on campus and interviews 100 students in the cafeteria.
b. A pollster wants to interview 20 gas station managers in Baltimore. He posts a list of all such managers on his wall, closes his eyes, and tosses a dart at the list 20 times. He interviews the people whose names the dart hits. |
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m102926 | Which parametric tests do the following tests replace?
(a) Sign test
(b) Wilcoxon signed-ranks T test
(c) Mann-Whitney U test
(d) Kruskal-Wallis H test
(e) Friedman test |
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m102927 | Which technique for gathering data (observational study or experiment) do you think was used in the following studies? Explain.
(a) The U.S. Census Bureau tracks population age. In 1900, the percentage of the population that was 19 years old or younger was 44.4%. In 1930, the percentage was 38.8%; in 1970, the percentage was 37.9%; and in 2000, the percentage in that age group was down to 28.5% (Reference: The First Measured Century, T. Caplow, L. Hicks, and B. J. Wattenberg).
(b) After receiving the same lessons, a class of 100 students was randomly divided into two groups of 50 each. One group was given a multiple-choice exam covering the material in the lessons. The other group was given an essay exam. The average test scores for the two groups were then compared. |
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m102928 | Which type of income statement-single-step or multiple-step-does The North West Company use? You can find its financial statements in Appendix A at the back of this textbook. |
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m102929 | Why are the degrees of freedom for the t distribution and the degrees of freedom for sample variance the same? |
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