Refer to the Teaching Psychology (May 1998) study of how external clues influence performance, presented in Exercise. Recall that two different forms of a midterm psychology examination were given, one printed on blue paper and the other on red paper. Grading only the difficult questions, the researchers found that scores on the blue exam had a distribution with a mean of 53% and a standard deviation of 15%, while scores on the red exam had a distribution with a mean of 39% and a standard deviation of 12%. Assuming that both distributions are approximately normal, on which exam is a student more likely to score below 20% on the difficult questions, the blue one or the red one?
Answer to relevant QuestionsOn the basis of data from the National Center for Health Statistics, N. Wetzel used the normal distribution to model the length of gestation for pregnant U.S. women (Chance, Spring 2001). Gestation has a mean length of 280 ...A. K. Shah published a simple approximation for areas under the normal curve in The American Statistician (Feb. 1985). Shah showed that the area A under the standard normal curve between 0 and z is a. Use Shah’s ...In Example, we use the computer to generate 1,000 samples, each containing n = 11 observations, from a uniform distribution over the interval from 150 to 200. Now use the computer to generate 500 samples, each containing n = ...A random sample of n = 100 observations is selected from a population with μ = 30 and σ = 16. a. Find μx-bar and σx-bar. b. Describe the shape of the sampling distribution of x-bar. c. Find P(x-bar ≥ 28). d. Find ...True or False. The sampling distribution of x-bar is normally distributed, regardless of the size of the sample n.
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