Question

Suppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.47 and a standard deviation of 1.5. Using the empirical rule, what percentage of American women have shoe sizes that are greater than 11.47? Please do not round your answer.

Answer 1

Answer:

2.5% of American women have shoe sizes that are greater than 11.47.

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 = 8.47

Standard deviation = 1.5

The normal distribution is symmetric, which means that half the measures are below the mean, and half are above the mean.

What percentage of American women have shoe sizes that are greater than 11.47?

11.47 = 8.47 + 2*1.5

This means that 11.47 is two standard deviations above the mean.

Of those measures below the mean, none are greater than 11.47.

Of those measures above the mean, 95% are between the mean and 11.47, and 5% are above. So

0.5*0.05 = 0.025

2.5% of American women have shoe sizes that are greater than 11.47.