Question

When Brooklyn runs the 400 meter dash, her finishing times are normally distributed with a mean of 76 seconds and a standard deviation of 3 seconds. Using the empirical rule, what percentage of races will her finishing time be between 70 and 82 seconds?

Answer 1

Using the Empirical Rule, it is found that her finishing time will be between 70 and 82 seconds in 95% of her races.

What does the Empirical Rule state?

It states that, for a normally distributed random variable:

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

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

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

In this problem, the mean is of 76 seconds and the standard deviation is of 3 seconds, then:

76 - 2 x 3 = 70.

76 + 2 x 3 = 82.

Which means that values between 70 and 82 seconds are within 2 standard deviations of the mean, hence the percentage is of 95%.

More can be learned about the Empirical Rule at brainly.com/question/24537145