In a test of a lifelong brand of tires, a survey revealed that the mean life was 38,997 miles and the standard deviation was 6,695 miles. If the shape of the population distribution is not known, approximately what percentage of the tires last less than 25,607 miles or greater than 52,387 miles? Enter percentage with a % sign.

Nothing more than ....%

There was an online resource that told me to find the standard deviation by using the following method:

(38,997-25607)/6,995=2

Question

In a test of a lifelong brand of tires, a survey revealed that the mean life was 38,997 miles and the standard deviation was 6,695 miles. If the shape of the population distribution is not known, approximately what percentage of the tires last less than 25,607 miles or greater than 52,387 miles? Enter percentage with a % sign.

Nothing more than ....%

There was an online resource that told me to find the standard deviation by using the following method:

(38,997-25607)/6,995=2