The life expectancy of a certain product is normally distributed with a mean of 48 months and a standard deviation of 12 months.
Ninety-five percent of the hair dryers will have a life expectancy of at least how many months?
a. 28.3
b. 34.8
c. 46.4
d. 67.7
e. 49.6
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Ninety-five percent of the hair dryers will have a life expectancy of at least how many months?
a. 28.3
b. 34.8
c. 46.4
d. 67.7
e. 49.6
show work
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67.7. Look up 0.95 in a z table, multiply the value you find by the standard deviation of 12 months, add that to the mean of 48.