Question

A quality control expert at Glotech computers wants to test their new monitors. The production manager claims they have a mean life of 73 months with a standard deviation of 7 months.

If the claim is true, what is the probability that the mean monitor life would be greater than 72.1 months in a sample of 109 monitors? Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean = = 73

standard deviation = = 7

n = 109

=    = 73

= / n = 7 / 109 = 0.6705

P( > 72.1 ) = 1 - P( <72.1 )

= 1 - P[( - ) / < (72.1 - 73) / 0.6705]

= 1 - P(z <-1.34)

= 1 - 0.0901 = 0.9099

probability 0.9099