Question

Suppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.118.11 and a standard deviation of 1.461.46. Using the empirical rule, what percentage of American women have shoe sizes that are at least 11.0311.03?

Answer 1

Answer:

2.5% of American women have shoe sizes that are at least 11.03.

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 = 8.11

Standard deviation = 1.46

Using the empirical rule, what percentage of American women have shoe sizes that are at least 11.03?

11.03 = 8.11 + 2*1.46

So 11.03 is two standard deviations above the mean.

The empirical rule states that 95% of the measures are within 2 standard deviation of the mean. Since the distribution is symetric, of those 5% farther than two standard deviations of the mean, 2.5% are higher than 2 standard deviations above the mean and 2.5% are lower than 2 standard deviations below the mean.

So 2.5% of American women have shoe sizes that are at least 11.03.