Assume that the heights of men are normally distributed with a mean of 66.9 inches and a standard deviation of 2.1inches. If 36 men are randomly selected, find the probability that they have a mean height greater than 67.9 inches.
A. 0.0021
B. 0.0210
C. 0.9979
D. 0.9005

Respuesta :

Answer:

A. 0.0021

Step-by-step explanation:

Given that the heights of men are normally distributed with a mean of 66.9 inches and a standard deviation of 2.1inches.

Sample size = 36

Std dev of sample = [tex]\frac{2.1}{\sqrt{36} } =0.35[/tex]

The sample entries X the heights are normal with mean= 66.9 inches and std deviation = 0.35 inches

Or we have

Z = [tex]\frac{x-66.9}{0.35}[/tex]

Hence the probability that they have a mean height greater than 67.9 inches

=[tex]P(X>67.9)\\=P(Z>\frac{1}{0.35)} \\=0.00214[/tex]

So option A is right answer.

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