Tires of a particular brand have a lifetime mean of 29,000 miles and a standard deviation of

Question:

Tires of a particular brand have a lifetime mean of 29,000 miles and a standard deviation of 3,000 miles.
a. It can be guaranteed that 75% of the lifetimes of tires of this brand will be in what interval?
b. Using the empirical rule, it can be estimated that approximately 95% of the lifetimes of tires of this brand will be in what interval?