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Probability, Percentile, and Standard Deviation

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The IQ scores are normally distributed with a mean of 100 and a standard deviation of 15.

1. What is the probability that a random person has an IQ between 85 and 115?
2. Find the 90th percentile of the IQ distribution.
3. If a random sample of 100 people is selected, what is the standard deviation of the sample mean?

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This solution helps with a problem regarding probability, percentile and standard deviation.

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