# Normal probability calculation based on Z score

Individual scores of a placement examination are normally distributed with a mean of 84.2 and a standard deviation of 12.8.

If the score of an individual is randomly selected, find the probability that the score will be less than 90.0.

If a random sample of size n = 20 is selected, find the probability that the sample mean will be less than 90.0.

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#### Solution Summary

The solution provides step by step method for the calculation of probability from Z score. Formula for the calculation and Interpretations of the results are also included.

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