A credit card company wants to estimate the average balance of its customers to within $15...
A credit card company wants to estimate the average balance of its customers to within $15 of the true value, with a 95% confidence. Find the minimum required sample size, if the standard deviation is $43.
Homework Answers
Solution:
Given in the question
Margin of error = 15/2 =7.5
Standard deviation = 43
Zalpha/2 = 1.96
Margin of error can be calculated as
Margin of error = Zalpha/2 * SD/sqrt(n)
7.5 = 1.96*43/sqrt(n)
N = (1.96*43/7.5)^2
No. Of sample = (11.2373)^2 = 127
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