# Histogram and Level of Significance

A civil service exam is given to 200 job applicants. In recent years, grades have followed a normal distribution with mean 66.5 and variance 100. The grades of the job applicants are distributed as follows:

Grades Observed Frequency

Under 49.5 22

49.5 - 59.5 38

59.5 - 69.5 56

69.5 - 79.5 50

79.5 and over 34

a) Graph the observed frequencies on a histogram. Does the histogram appear to have the shape of a normal distribution with mean 66.5 and variance 100?

b) Test the hypothesis that the data came from a normal distribution with mean 66.5 and variance 100. Use a 5% level of significance.

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#### Solution Summary

The solution graphs the observed frequencies on a histogram, and tests the data .

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