Question

In a normally distributed data set a mean of 55 where 95% of the data fall between 47.4 and 62.6, what would be the standard deviation of that data set?

Answer 1

Answer:

The standard deviation of that data set is 3.8

Step-by-step explanation:

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

Mean = 55

95% of the data fall between 47.4 and 62.6. This means that 47.4 is 2 standard deviations below the mean and 62.6 is two standard deviations above the mean.

Using one of these points.

55 + 2sd = 62.6

2sd = 7.6

sd = 7.6/2

sd = 3.8

The standard deviation of that data set is 3.8