*** *** 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