Question 262939: In a study of the life expectancy of 500 people in a certain geographic region,the mean age at death was 72.0 years, and the standard deviation was 5.3 years. If a sample of 50 people from this region is selected, find the probability that the mean life expectancy will be less than 70 years. They want all work to be shown and I don't even no where to begin. Thanks for your help
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! In a study of the life expectancy of 500 people in a certain geographic region,the mean age at death was 72.0 years, and the standard deviation was 5.3 years.
If a sample of 50 people from this region is selected, find the probability that the mean life expectancy will be less than 70 years.
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t(70) = (70-72)/[5.3/sqrt(50)] = -2.6683..
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P(x< 70) = P(t<-2.6683 when df = 49) = tcdf(-100,-2.6683,49) = 0.0052
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Cheers,
Stan H.
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