Chapter 2: Q 30. (page 108)
A uniform distribution What is the mean of the density curve pictured in Exercise ? What is the median?
Short Answer
The mean and median are equal to
Chapter 2: Q 30. (page 108)
A uniform distribution What is the mean of the density curve pictured in Exercise ? What is the median?
The mean and median are equal to
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Get started for freeSAT versus ACT Eleanor scores on the SAT Mathematics test. The distribution of SAT scores is
symmetric and single-peaked, with mean and standard deviation . Gerald takes the American College Testing (ACT) Mathematics test and scores 27. ACT scores also follow a symmetric, singlepeaked distribution—but with mean and standard deviation . Find the standardized scores for both students. Assuming that both tests measure the same kind of ability, who has the higher score?
About what percent of the cockroaches have weights between and grams?
(a)
(b)
(c)
(d)
(e)
Baseball salaries Brad Lidge played a crucial role as the Phillies’ “closer,” pitching the end of many games throughout the season. Lidge’s salary for the season was
(a) Find the percentile corresponding to Lidge’s salary. Explain what this value means.
(b) Find the z-score corresponding to Lidge’s salary. Explain what this value means.
Blood pressure Larry came home very excited after a visit to his doctor. He announced proudly to his wife, “My doctor says my blood pressure is at the percentile among men like me. That means I’m better off than about of similar men.” How should his wife, who is a statistician, respond to Larry’s statement?
Normal is only approximate: ACT scores Scores on the ACT test for the 2007 high school graduating class had mean and standard deviation . In all, students in this class took the test. Of these, had scores higher than and another had scores exactly 27. ACT scores are always whole numbers. The exactly Normal distribution can include any value, not just whole numbers. What’s more, there is no area exactly above under the smooth Normal curve. So ACT scores can be only approximately Normal. To illustrate this fact, find
(a) the percent of ACT scores greater than .
(b) the percent of ACT scores greater than or equal to .
(c) the percent of observations from the distribution that are greater than 27. (The percent greater than or equal to is the same, because there is no area exactly over .)
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