In: Statistics and Probability
A quality control expert at Glotech computers wants to test their new monitors. The production manager claims they have a mean life of 83 months with a variance of 81. If the claim is true, what is the probability that the mean monitor life would be greater than 81.2 months in a sample of 146 monitors? Round your answer to four decimal places.
Solution :
Given that ,
mean =
= 83
2
= 81
standard deviation =
= 9
n = 146
= 83
=
/
n = 9/
146 = 0.74
P(
>81.2 ) = 1 - P(
<81.2 )
= 1 - P[(
-
) /
< (81.2-83) /0.74 ]
= 1 - P(z <-2.43 )
Using z table,
= 1 - 0.0075
probability= 0.9925