Question

A car is designed to last an average of 12 years with a standard deviation of 0.8 years.

What is the probability that a car will last less than 10 years?

0.621%
6.21%
93.79%
99.379%

Answer 1

10-12/0.8=-2.5
P(-2.5)=0.0062
0.62%

Answer 2

Borrowing from Will.H: "10-12/0.8=-2.5" is the z-score here, and is appropriate. How would you answer the question using this z-score?

z=(10-12)/0.8=-2.5

Answer 3

"Less than 10 years" here means anything from 0 to just under 10 years.