SOLUTION: A recent study of the lifetimes of cell phones found the average is 24.3 months. The standard deviation is 2.6 months. If a company provides its 35 employees with a cell phone, fin

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Question 1081726: A recent study of the lifetimes of cell phones found the average is 24.3 months. The standard deviation is 2.6 months. If a company provides its 35 employees with a cell phone, find the probability that the mean lifetime of these phones will be less than 23.9 months. Assume cell phone life is a normally distributed variable, the sample is taken from a large population and the correction factor can be ignored. . Round final answer to four decimal places and intermediate z-value calculations to two decimal places.
P(X <23.9)=
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
t df=34<(xbar-mean)/s/sqrt(n)
<(23.9-24.3)/2.6/sqrt(35)
<-0.4*sqrt(35)/2.6=-0.91
that probability is 0.1845.