Question

If n=300 and X=120, construct a 90% confidence interval estimate for the population proportion. Round to four decimal places as needed

Answer 1

sample success x =		120
sample size          n=		300
sample proportion p̂ =x/n=120/300=		0.400
std error se= √(p*(1-p)/n) =√(0.4*0.6/300) =		0.0283
for 90 % CI value of z=		1.645
margin of error E=z*std error   =		0.0465
lower bound=p̂ -E                       =		0.3535
Upper bound=p̂ +E                     =		0.4465

from above 90% confidence interval for population proportion =(0.3535 , 0.4465)