A national bank analysed a random sample of 365 cheque accounts at their Windhoek branch and found that 78 of them were

A national bank analysed a random sample of 365 cheque accounts at their Windhoek branch and found that 78 of them were overdrawn. Estimate, with 90% confidence, the proportion of all bank accounts at the Windhoek branch of the bank that were not overdrawn.

Solution file includes:

confprop08101701.pdf

Preview of confprop08101701.pdf

*** *** bank *** *** random *** *** 365 cheque accounts *** *** *** *** *** found that *** of them *** *** *** with *** *** *** *** of *** *** accounts at *** *** of the bank *** were *** *** that sample *** n= *** *** *** *** *** *** *** *** *** so X= 365 *** *** 287 *** *** *** proportion *** *** bank accounts at *** *** branch of *** *** that were not overdrawn is ^ p = X *** 287 *** *** *** *** *** *** *** 0 :9 . *** *** level of signicance is *** 0 *** *** )% *** interval *** population *** *** all *** accounts *** *** *** branch *** *** *** were not *** *** *** *** *** ^ p *** E *** *** ^ p (1 *** *** *** *** theZvalue *** an area *** *** upper tail of the standard normal probability *** critical value *** Zfor given level *** signicance is Z = *** *** 2= Z 0:05 = *** . 1ZCritical values 3.51.6401.643.5 0.050.90.05 The margin of *** for *** *** *** *** (1 ^ p ) n = *** :645 *** 0 :786 (1 *** 365 = *** *** : 90 *** *** *** *** for *** proportion is ^ p *** *** *** + *** *** 0:035 *** *** + *** *** :751 *** *** : Thus, 90% condence interval *** *** the true *** *** *** *** *** . 2