Solution :
Given that,
Population standard deviation = = 15
Margin of error = E = 0.1
At 95% confidence level the z is,
= 1 - 95%
= 1 - 0.95 = 0.05
/2 = 0.025
Z/2 = Z0.025 =
1.96
sample size = n = [Z/2*
/ E] 2
n = [ 1.96 * 15 / 0.1]2
Sample size = n = 86436
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