Acertain brand of automobile tire has a mean life span of 34000 miles and a standard deviation of 2400 miles. (assume the life spans of the tires have a bell-shaped distribution.)

the life spans of three randomly selected tires are 35000 miles, 37000 miles, and 31000 miles. find the z-score that corresponds to each life span.

z score for 35000 is 0.42
z score for 37000 is 1.25
z score for 31000 is -1.25

the life spans of three randomly selected tires are 31600 miles, 36400 miles, and 34000 miles. using the empirical rule, find the percentile that corresponds to each life span.

the life span 31600 miles corresponds to the
percentile.
the life span 36400 miles corresponds to the
percentile.
the life span 34000 miles corresponds to the
percentile.