1,000 cars in the parking lot are surveyed and the average or mean mileage is 30,000 on those cars. if the standard deviation is 5,000, how many cars would fall in the range of mileage of 25,000 to 35,000 approximately?

Z score for 25,000 = 25000 - 30,000 / 5000

= -1

for 35,000 it is 35000 - 30000/ 5000 = 1

we can now look up the probabilty of cars having range 25000- 35000 on Standard Normal tables using these z scores:-

It comes to 68.27 %

out of the 1,000 cars you'd expect 680 to be within this range of mileage.

Answer 680