Question

An earlier study determined that 60% of women aged over 50 have annual mammograms. To see if this proportion is still valid we send surveys to 400 women aged over 50. Of the 60 who respond, 48 say they have annual mammograms. Use the " Plus Four" method to estimate the current proportion of women aged over 50 who say they get annual mammograms with a 95% confidence interval. (round to the 4th decimal place)

Answer 1

Answer:

The required confidence interval is (0.68 , 0.8825)

Explanation:

n=48

Confidence interval 95%

Method p = 48+2 / 60+4 = 0.781250

SE = $\sqrt{p*(1-p)/60+4}$ = 0.0516748

confidence interval p ± 1.95996*$\sqrt{p*(1-p)/60+4}$ = (0.679969,0.882531)