SOLUTION: Suppose the age at death for politicians can be modeled by an approximately normal distribution with a mean of 72.7 years and a standard deviation of 7.2 years. Calculate the z-

Question 1155690: Suppose the age at death for politicians can be modeled by an approximately normal distribution with a mean of 72.7 years and a standard deviation of 7.2 years.
Calculate the z-score representing the longest 20% of life expectancy for politicians. (Round your answer to two decimal places.)
Calculate the value (in years) representing the top 20% of life expectancies. (Round your answer to one decimal place.)
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The z-score =(x-mean)/sd
z(.20)=-0.842 so upper 20% is z=+0.84 (z (.80))
z=(x-mean)/sd
.84=(x-72.7)/7.2
6.05=x-72.7
x=78.75 or 78.8 years
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