A large bank believes that one-third of its checking customers have used at least one of the bank\'s other services during the past year. How large a sample is required to estimate the actual proportion within a range of a plus and minus 0.04? Use the 98% level of confidence (show work by hand). (2 points) Solution Given a=0.02, |Z(0.01)|=2.33 (check standard normal table) So n=(Z/E)^2*p*(1-p) =(2.33/0.04)^2*(1/3)*(2/3) =754.0139 Take n=755.

1. A large bank believes that one-third of its checking customers have used at least one of the
bank's other services during the past year. How large a sample is required to estimate the
actual proportion within a range of a plus and minus 0.04? Use the 98% level of
confidence (show work by hand). (2 points)
Solution
Given a=0.02, |Z(0.01)|=2.33 (check standard normal table) So n=(Z/E)^2*p*(1-p)
=(2.33/0.04)^2*(1/3)*(2/3) =754.0139 Take n=755