Question

During routine​ screening, a doctor notices that 18​% of her adult patients show higher than normal levels of glucose in their bloodlong dash—a possible warning signal for diabetes. Hearing​ this, some medical researchers decide to conduct a​ large-scale study, hoping to estimate the proportion to within 4​% with 99​% confidence. How many randomly selected adults must they​ test? The number of adults that should be tested is nothing .

Answer 1

Formula :

Where,

where , E is margin of error = 4% = 0.04

p : previous estimate for population proportion = 18% = 0.18

: Critical value for given confidence level.

Given confidence level = 99% = 0.99

Significance level = 1 - 0.99 = 0.01

               { Using Excel, =NORMSINV(0.005) = 2.5758 }

So sample size n is,

n = 613 ( Rounded to the next integer )