A manufacturer knows that their items have a normally distributed lifespan, with a mean of 4.5 years, and standard deviation of 1.3 years.

The 10% of items with the shortest lifespan will last less than how many years?

Give your answer to one decimal place

Here is as far as I got

m=4,5

deviation= 1.3

10%= .10

Then I looked for .10 on the z score and it was -1.28

Then -1.28-4.5/1.3 -4.44 which is incorrect.

Can someone explain what steps I did wrong and what I need to do to get the correct answer?