Question

The bank in Cobden, Ontario, has 650 chequing account customers. A recent sample of 50 of these customers showed 26 to have a Visa card with the bank.

Construct the 99% confidence interval for the proportion of chequing account customers who have a Visa card with the bank. (Round the final answers to 3 decimal places.)

The 99% Confidence interval for the proportion of chequing account customers is between___and___.

Answer 1

Sample proprotion = 26 / 50 = 0.52

99% confidence interval for p is

- Z/2 * sqrt [ ( 1 - ) / n] < p < + Z/2 * sqrt [ ( 1 - ) / n]

0.52 - 2.576 * sqrt [ 0.52 ( 1 - 0.52) / 50] < p < 0.52 + 2.576 * sqrt [ 0.52 ( 1 - 0.52) / 50]

0.338 < p < 0.702

99% CI is between 0.338 and 0.702