Question

In a survey of 3230 adults aged 57 through 85​ years, it was found that 81.4​% of them used at least one prescription medication. Complete parts​ (a) through​ (c) below.

a. How many of the 3230 subjects used at least one prescription​ medication?

b. Construct a​ 90% confidence interval estimate of the percentage of adults aged 57 through 85 years who use at least one prescription medication.

​ %less than<less than< ​%

Answer 1

a. Here p=0.814 and n=3230

Hence x=np=3230*0.814=2629.22=2629

So 2629 of the 3230 subjects used at least one prescription​ medication.

b. z value for 90% CI is 1.645 as P(-1.645<z<1.645)=0.90

So Margin of Error is

Hence CI is

So a​ 90% confidence interval estimate of the percentage of adults aged 57 through 85 years who use at least one prescription medication is 0.803<p<0.825