SOLUTION: Adult Intelligence Quotient scores have been demonstrated to be normally distributed with a mean of 100 and a standard deviation of 15. Suppose that nine adults are chosen at rand

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Question 375737: Adult Intelligence Quotient scores have been demonstrated to be normally distributed with a mean of 100 and a standard deviation of 15. Suppose that nine adults are chosen at random and their Intelligence Quotients are measured. Determine the probability that the mean Intelligence Quotient score of the nine adults is greater than or equal to 118.
Answer by ewatrrr(24785) About Me  (Show Source):
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Hi

*Note: z+=+%28x+-+mu%29%2F%28sigma%2Fsqrt%28n%29%29

z+=+%28118+-+100%29%2F%2815%2F3%29

z = 18/5 = 3.6

P(z ≥ 3.6) = 1 - .9998 =.00016