Question

There are approximately one billion smartphone users in the world today. In the United States, the ages of smartphone users between 13 to 55 approximately follow a normal distribution with approximate mean and standard deviation of 37 years and 8 years, respectively. Using the 68-95-99.7 Rule, what percent of smartphone users are between the ages of 29 and 45?

Answer 1

By the 68-95-99.7 Rule, 68% of smartphone users are between the ages of 29 and 45.

Explanation:

The 68-95-99.7 Rule states that:

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

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

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

Approximate mean and standard deviation of 37 years and 8 years, respectively:

What percent of smartphone users are between the ages of 29 and 45?

29 is 1 standard deviation below the mean.

45 is 1 standard deviation above the mean.

29 and 45 are within 1 standard deviation of the mean. So, by the 68-95-99.7 Rule, 68% of smartphone users are between the ages of 29 and 45.