ahmedelsayed

The mean life of a certain brand of auto batteries is 44 months with a standard deviation of 1 month. Assume that the lives of all auto batteries of this brand have a bell-shaped distribution. Using the empirical rule, find the percentage of auto batteries of this brand that have a life of 41 to 47 months. Round your answer to one decimal place.

The mean useful life of car batteries is 47 months. They have a standard deviation of 2. Assume the useful life of batteries is normally distributed.

1. 
   Calculate the percent of batteries with a useful life of less than 43 months. (Round your answer to the nearest hundredth percent.)
   b. Calculate the percent of batteries that will last longer than 53 months.(Round your answer to the nearest hundredth percent.)
2. 
   Percent of batteries ____ %
3. Percent of batteries ____ %