090 005 050 010 The minimum sample size n required to estima

0.90

0.05

0.50

0.10

The minimum sample size n required to estimate a population mean with 95% confidence and the desired margin of error 1.5 was found to be 198. Which of the following is the approximate value of the assumed estimate of the population standard deviation?

164.6326

12.8309

10.7688

115.9671

Solution

1.

We assume the value that will maximize the sample size,

p^ = 0.50 [ANSWER, C]

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2.

As

E = z*s/sqrt(n)

Then

s = E*sqrt(n)/z

As z = 1.959963985 for 95% confidence, then

s = 1.5*sqrt(198)/1.959963985 = 10.7688 [ANSWER, C]