The average life of a certain type of small motor is 10 years with a standard de
ID: 3217303 • Letter: T
Question
The average life of a certain type of small motor is 10 years with a standard deviation of 2 years. The manufacturer replaces free all motors that fail while under guarantee. If she is willing to replace only 3% of the motors that fail, how long a guarantee should be offered? Assume that the lifetime of a motor follows a normal distribution. The average life of a certain type of small motor is 10 years with a standard deviation of 2 years. The manufacturer replaces free all motors that fail while under guarantee. If she is willing to replace only 3% of the motors that fail, how long a guarantee should be offered? Assume that the lifetime of a motor follows a normal distribution.Explanation / Answer
Here mean=10 and sd=2
We know that P(X<x)=0.03
Uing z table we get P(Z<z)=0.03 for z=-1.881
As we know z=x-mean/sd
so x=-1.881*2+10=6.238 so around 75 months
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