Question

If you want t be 95% confident of estimating the population mean to within sampling error of +/- 6 and the standard deviation is assumed to be 19, what sample size is required?

Answer 1

SOLUTION :

From given data,

sampling error =E =   6

standard deviation = = 19

95%

= 95/100 = 0.95

The area under the curve is

1- = 1-0.95 = 0.05

Using this area we find out Z value =1.960

Sample size = N = [(z*) / E ] ²

= [(1.960 * 19 ) / 6] ²

= (6.2067)²

= 38.523

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