in a survey of 3465 adults 1480 say they have started paying

in a survey of 3465 adults, 1480 say they have started paying bills online in the last year. construct a 99% confidence interval for the population proportion.

Solution

Confidence Interval Estimate for the Proportion

Data

Sample Size

3465

Number of Successes

1480

Confidence Level

99%

Intermediate Calculations

Sample Proportion

0.4271

Z Value

2.5760

Standard Error of the Proportion=sqrt(0.4271*(1-0.4271)/3465))=

0.0084

Interval Half Width= 2.576*0.0084=

0.0216

Confidence Interval

Interval Lower Limit =( 0.4271-0.0216) =

0.4055

Interval Upper Limit =( 0.4271+0.0216) =

0.4487