Question

A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 390 babies were​born, and 312 of them were girls.

Use the sample data to construct a 99% confidence interval estimate of the percentage of girls born.

Based on the​ result, does the method appear to be​ effective?

Answer 1

sample success x =	312
sample size          n=	390
sample proportion p̂ =x/n=	0.8000
std error se= √(p*(1-p)/n) =	0.0203
for 99 % CI value of z=	2.576
margin of error E=z*std error   =	0.0522
lower bound=p̂ -E                       =	0.7478
Upper bound=p̂ +E                     =	0.8522
from above 99% confidence interval for population proportion =(0.748,0.852)

(since above interval has all values above 0.50 , therefore  method appear to be​ effective in  increasing the probability of conceiving a girl