The scores on the Wechsler Intelligence Scale for Children (WISC) are thought to be normally distributed with a standard deviation of 10. A simple random sample of 25 children is taken, and each is given the WISC. The sample mean for the 25 scores is 104.32. Based on these data, what is a 95% confidence interval for the population mean. (100.4,108.2) (103.5,105.1) (84.7,123.9) (101.0,107.6)
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We are given the sample mean (x̄) = 104.32, the standard deviation (σ) = 10, and the sample size (n) = 25. Show more…
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The scores of a certain population on the Wechsler Intelligence Scale for Children (WISC) are thought to be Normally distributed with mean μ and standard deviation σ = 10. A simple random sample of 25 children from this population is taken and each is given the WISC. The mean of the 25 scores is x-bar = 104.32. Suppose a histogram of the 25 WISC scores is the following: Based on this histogram, we would conclude that a 95% confidence interval of 104.32 ± 3.92 is: actually a 99% confidence interval. actually a 90% confidence interval. not very reliable. very reliable.
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The Wechsler Intelligence Scale for Children (WISC) is an intelligence test for children. Scores (represented by random variable X) on this test are normally distributed with a mean of µ = 100 and a standard deviation of σ = 15. In the following questions, make sure you use proper formal notation. a) What is the probability that a randomly selected child obtains a score of greater than 121? b) Suppose that a random sample of 50 children is drawn, and they all take the WISC. What is the mean and standard deviation of the distribution of the sample mean X̄? c) What is the probability that X̄ > 121 given the random sample of 50 children?
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