uppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.2 and a standard deviation of 1.49. Using the empirical rule, what percentage of American women have shoe sizes that are less than 12.67

Question

Cricket

Mathematics

8 November, 09:19

uppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.2 and a standard deviation of 1.49. Using the empirical rule, what percentage of American women have shoe sizes that are less than 12.67

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Roselyn Rich · Answer 1

99.85% of American women have shoe sizes that are less than 12.67

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 = 8.2

Standard deviation = 1.49

Using the empirical rule, what percentage of American women have shoe sizes that are less than 12.67

12.67 = 8.2 + 3*1.49

12.67 is 3 standard deviations above the mean.

Since the normal distribution is symmetric, 50% of the measures are below the mean and 50% are above. Of those 50% above, 99.7% are between the mean and 12.67. So

0.5 + 0.997*0.5 = 0.9985

99.85% of American women have shoe sizes that are less than 12.67