Question

When Carson runs the 400 meter dash, his finishing times are normally distributed with a mean of 63 seconds and a standard deviation of 0.5 seconds. Using the empirical rule, what percentage of races will his finishing time be between 62 and 64 seconds?

Answer 1

Answer: in 95% of races, his finishing time will be between 62 and 64 seconds.

Step-by-step explanation:

The empirical rule states that for a normal distribution, nearly all of the data will fall within three standard deviations of the mean . The empirical rule is further illustrated below

68% of data falls within the first standard deviation from the mean.

95% fall within two standard deviations.

99.7% fall within three standard deviations.

From the information given, the mean is 63 seconds and the standard deviation is 5 seconds.

2 standard deviations = 2 × 0.5 = 1

63 - 1 = 62 seconds

63 + 1 = 64 seconds

Therefore, in 95% of races, his finishing time will be between 62 and 64 seconds.