A bank randomly selected 240 checking account customers and found that 115 of them also had savings accounts at this same bank. Construct a 98% confidence interval for the true proportion of checking account customers who also have savings accounts. (Give your answers correct to three decimal places.)

Question

anonymous · Answer

phat +/- E
E= z (alpha/2) * sqrt ( (phat*qhat)/n )
z (alpha/2) = 2.33
phat = 115/240
qhat = 125/240
n=240
E=.0751
phat - E = .404
phat + E = .554
.404<p<.554