In a survey of 688 US adults with children 249 of them repor

In a survey of 688 US adults with children, 249 of them reported that they saved money for their children

p = 249/688 = 0.362

q = 1-p = 0.638

sd = sqrt(n*p*q) = sqrt( 688*0.638 * 0.362) = 158.89

for 0.05 SL,

P(-z<Z<z) > 0.95

P(0<Z<z) > 0.95/2 > 0.485

z < 2.16 or z > -2.16

(x - 249)/158.89/sqt(688) < 2.16 or (x - 249)/158.89/sqt(688) > -2.16

x - 249 < 13.08 or x-249 > -13.08

x < 262.08 or x>235.92

so,

235.92<x<262.08

235.92/688 < p < 262.08/688

0.343 < p < 0.381

so,

it is more than 33%