Question

You are concerned that you did not sample the correct number of​ 5-year-olds. You know that...

You are concerned that you did not sample the correct number of​ 5-year-olds. You know that the standard deviation of all​ 5-year-old females' heights is 0.75 inches. You want to be​ 99% confident that the mean is correct within 0.25 inches.

How many​ 5-year-old females should you​ sample?

Is a sample of 80 large​ enough? Yes No

Math   Statistics-And-Probability   
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Answer #1

Solution :

Given that,

= 0.75

E = 0.25

At 99% confidence level the z is ,

  = 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z/2 = Z0.005 = 2.576

sample size = n = (Z/2* /E)2

= (2.576 * 0.75 / 0.25 )2

n= 59.72

n= 60

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