The population standard deviation is estimated to be $300. If a 98% confidence interval is used and an interval of +/-$75 is desired, how many cardholders should be sampled?

Answer 1

98% confidence interval = ± 2.33 Standard Error of the mean (SEm) = ± 75

SEm = SD/√(n-1)

(If n is large, do not need to subtract 1.)

I'll let you do the calculations.