Question

A manufacturer knows that their items have a normally distributed lifespan, with a mean of 11.5 years, and standard deviation of 1.9 years.

If you randomly purchase one item, what is the probability it will last longer than 12 years?

Answer 1

Answer:

39.74 %

Step-by-step explanation:

12 years - 11.5  = .5 years

.5 / 1.9 = .2631 S.D   above the mean

  From z-score table this corresponds to .6026

          60.26 are BELOW this life span

             39.74 % are above 12 years