Question

A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 325 babies were​ born, and 260 of them were girls. Use the sample data to construct a 99​% confidence interval estimate of the percentage of girls born.

__ < p < __

Answer 1

Solution :

Given that,

Point estimate = sample proportion = = x / n = 260 / 325 = 0.800

Z_/2 = 2.576

Margin of error = E = Z _{/ 2} * (( * (1 - )) / n)

= 2.576 * (((0.800 * 0.200) / 325)

= 0.057

A 99% confidence interval for population proportion p is ,

- E < p < + E

0.800 - 0.057 < p < 0.800 + 0.057

0.743 < p < 0.857