Question

The scores on a quiz are normally distributed. The mean of the quiz is 93 and the standard deviation is 4.2. By using the Empirical rule, what scores fall 1 standard deviation from the mean?

89 and 101

84.6 and 101.4

89.2 and 96.8

88.8 and 97.2

Answer 1

any score that lies between 88.8 and 97.2 is within one std. dev. of the mean

Explanation:

One std. dev. above the mean would be 93 + 4.2, or 97.2. One std. dev. below the mean would be 93 - 4.2, or 88.8.

So: any score that lies between 88.8 and 97.2 is within one std. dev. of the mean.