Question

Nordic air conditioners last an average of fifteen years with a population standard deviation of two years, following a normal distribution. Nordic wants to offer a warranty on their air conditioners and they can’t afford to replace any more than 4% of air conditioners. How long should the warranty be?

a. 11.0

b. 11.5

c. 15.0

d. 18.0

e. 18.5

Answer 1

X : average life if Nordic air conditioners .

X ~ N ( 15 , 2 )

let the warranty be a years.

according to the problem,

[ in any blank cell of excel type =NORMSINV(0.04)]

his warranty should be of 11.5 years.

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