# Sampling methods and central limit theorem

The mean score of a college entrance test is 500, the standard deviation is 75 and the scores are normally distributed.

a. What percent of the students scored below 320?

b. What percent of the students scored between 400 and 525?

c. Twenty percent of the students had a test score above what score?

https://brainmass.com/statistics/central-limit-theorem/sampling-methods-central-limit-theorem-62700

#### Solution Preview

Let X represent the score of the college entrance test. From the condition, the mean of X is m=500, the standard deviation of X is d=75. X satisfies the normal distribution. So we can set Y=(X-m)/d=(X-500)/75, then Y ...

#### Solution Summary

Solution provides detailed response to three questions regarding standard deviation of a college entrance test.

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