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Statistics - Value - Probability

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1. What value represents the 25th percentile?

2. A normal distribution has a mean of 80 and a standard deviation of 14. Determine the value above which 80% of the values will occur.

3. A normal population has a mean of 75 and a standard deviation of 5. You select a sample of 40. Compute the probability the sample mean is:
a) Less than 74
b) Between 74 and 76
c) Between 76 and 77
d) Greater than 77

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Solution Summary

The probability value in statistics is determined. A complete, neat and step-by-step solution is provided.

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(1) 25 th percentile means the area to the left of the corresponding z- score mustbe 25%; that is, the p- value must be 0.25

P(z < a) = 0.25 for a = -0.6745

The 25 ...

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