Question

In a survey of

1001

​adults, a polling agency​ asked, "When you​ retire, do you think you will have enough money to live comfortably or not. Of the

10011

​surveyed,

522

stated that they were worried about having enough money to live comfortably in retirement. Construct a

9090​%

confidence interval for the proportion of adults who are worried about having enough money to live comfortably in retirement.

Answer 1

Sample proportion = 522 / 1001 = 0.521

90% confidence interval for p is

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

0.521 - 1.645 * sqrt( 0.521 * 0.479 / 1001 ) < p < 0.521 + 1.645 * sqrt( 0.521 * 0.479 / 1001 )

0.495 < p < 0.547

90% CI is ( 0.495 , 0.547 )