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38 votes
38 votes
Suppose the heights of the members of a population follow a normaldistribution. If the mean height of the population is 72 inches and thestandard deviation is 3 inches, 95% of the population will have a height within which range?

User Paul Calabro
by
2.7k points

1 Answer

17 votes
17 votes

We get that


\begin{gathered} P(-a\le Z\le a)=0.95 \\ 1-2\cdot P(Z\le-a)=0.95 \\ P(Z\le-a)=0.025 \\ -a=-1.96\rightarrow a=1.96 \\ 1.96=(X-72)/(3) \\ X_2=77.88 \\ X_1=66.12 \end{gathered}

So the answer is A

User Ronny Shibley
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2.8k points
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