# Statistics - Probability

The life expectancy of a brand of hair dryer is normally distributed with a mean of 4 years and a standard deviation of 8 months.

a. What is the probability that the hair dryer will be in working condition for more than 5 years?

b. What is the minimum and maximum life expectancy of the middle 90% of hte hair dryers?

https://brainmass.com/statistics/probability/probability-hair-dryer-example-253107

#### Solution Preview

m = 4, s = 8/12 = 2/3

(a) x = 5

z = (x - m)/s = (5 - 4)/(2/3) = 1.5

P(x > 5 years) ...

#### Solution Summary

A complete, neat and step-by-step solution is provided in the attached file.

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