Answer:
0.135% or 0.00135
Explanation:
• The population mean height = 68 inches
,• The population standard deviation = 4 inches
,• Sample Size, n = 36
First, find the sample standard deviation:
[tex]\sigma_x=\frac{\sigma}{\sqrt{n}}=\frac{4}{\sqrt{36}}=\frac{4}{6}=\frac{2}{3}[/tex]Next, for X=70, find the z-score:
[tex]\begin{gathered} z-score=\frac{X-\mu}{\sigma_x} \\ z=\frac{70-68}{2\/3}=\frac{2}{2\/3}=3 \end{gathered}[/tex]Since we are looking for the probability that their average height is more than 70 inches, we need to find:
• P(X>70)=P(z>3)
Using the z-score table:
[tex]P(z>3)=0.0013499[/tex]The probability that their average height is more than 70 inches is 0.135%.
