When Dalvin runs the 400 meter dash, his finishing times are normally distributed with a mean of 65 seconds and a standard deviation of 1 second. Using the empirical rule, what percentage of races will his finishing time be between 64 and 66 seconds?

[85, 95] seconds

Step-by-step explanation:

The empirical rule says 95% of the distribution is within 2 standard deviations of the mean. Two standard deviations is 2·(2.5 s) = 5 s, so 95% of her times are in the range 90 ±5 s. As an interval, that is [85, 95] seconds.

68%.

Step-by-step explanation:

Dalvin's finishing time is normally distributed with a mean of 65 seconds and a standard deviation of 1 second.

Under the empirical rule, 68% of the results will be within 1 standard deviation.

Since the standard deviation is 1 second, 68% of Dalvin's finishing time will be between 64 and 66 seconds.