Week_4_Answers

Week_4_Answers - DUE Date: 9/23 Make sure to show all work....

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DUE Date: 9/23 Name:________________________ Make sure to show all work. Homework #3 When a series of values takes on some distribution, it is common to describe it in terms of a distribution and parameters that fit the data. IQ tests, for example, are rescaled so that results are normally distributed with a mean of 100 and a standard deviation of 15. Taken a step further, this implies that about 99.5% of people who take an IQ test will get a score between 55 and 145, about 95% will score between 70 and 130, and so on. The variance for such a test would be 225, so we might write that IQ ~ Normal(100, 225). 1) In a normal distribution, what proportion of the scores fall within the interval between μ and one standard deviation above μ ? (Equivalently, in the IQ example above, what fraction of the population would you expect to score between 100 and 115?) a. .8413 b. .6826 c. .4143 d. .1359 e. .3414 2) In a normal distribution, .9544 of the scores will be located in the interval between __. a. μ plus 2σ b. μ plus 1σ and μ minus 2σ c. μ plus 2σ and μ minus 3σ d. μ plus 2σ and μ minus 2σ e. μ plus 1σ 3) If a distribution is normal with µ = 50 and σ = 10, then what proportion of the scores will fall between 40 and 60 (µ ± σ)? a. .1359
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Week_4_Answers - DUE Date: 9/23 Make sure to show all work....

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