The Shelf Life of a Battery Produced by One Major

Multiple Choice

The shelf life of a battery produced by one major company is known to be normally distributed, with a mean life of 3.5 years and a standard deviation of 0.75 years. What range of years contains 68% of all battery shelf lives?

A) 2 to 5 years
B) 2.5 to 4.5 years
C) 2.83 to 4.17 years
D) 2.75 to 4.25