Chapter 6: Q.31 (page 357)
Better readers?() Did students have higher reading scores after participating in the chess program? Give appropriate statistical evidence to support your answer.
Short Answer
Yes, students are getting higher marks.
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Chapter 6: Q.31 (page 357)
Better readers?() Did students have higher reading scores after participating in the chess program? Give appropriate statistical evidence to support your answer.
Yes, students are getting higher marks.
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Ms. Hall gave her class a -question multiple-choice quiz. Let the number of questions that a randomly selected student in the class answered correctly. The computer output below gives information about the probability distribution of . To determine each student鈥檚 grade on the quiz (out of ), Ms. Hall will multiply his or her number of correct answers by . Let the grade of a randomly chosen student in the class.
(a) Find the median of . Show your method.
(b) Find the IQR of . Show your method.
(c) What shape would the probability distribution of have? Justify your answer
80. More lefties Refer to Exercise 72.
(a) Find the probability that exactly students in the sample are left-handed. Show your work.
(b) Would you be surprised if the random sample contained or more left-handed students? Compute and use this result to support your
answer.
84. Lie detectors Refer to Exercise 82. Let the number of people who the lie detector says are telling the truth.
(a) Find . How is this related to? Explain.
(b) Calculate and. How do they compare with and ? Explain why this makes sense.
Checking for survey errors One way of checking the effect of undercoverage, nonresponse, and other sources of error in a sample survey is to compare the sample with known facts about the population. About % of American adults identify themselves as black. Suppose we take an SRS of American adults and let be the number of blacks in the sample.
(a) Show that is approximately a binomial random variable.
(b) Check the conditions for using a Normal approximation in this setting.
(c) Use the Normal approximation to 铿乶d the probability that the sample will contain between and blacks. Show your work.
To collect information such as passwords, online criminals use 鈥渟poofing鈥 to direct Internet users to fraudulent Web sites. In one study of Internet fraud, students were warned about spoofing and then asked to log in to their university account starting from the university鈥檚 home page. In some cases, the login link led to the genuine dialog box. In others, the box looked genuine but in fact was linked to a different site that recorded the ID and password the student entered. An alert student could detect the fraud by looking at the true Internet address displayed in the browser status bar below the window, but most just entered their ID and password. Is this study an experiment? Why? What are the explanatory and response variables?
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