Question

Construct a confidence interval of the population proportion at the given level of confidence. x equals x= 120 120​, n equals n= 1100 1100​, 90 90​% confidence

Answer 1

x                    =				120
sample size		n                    =		1100
sample proportion     p̂		x/n=		0.1091
std error       =Se		=√(p*(1-p)/n) =		0.0094
for 90 % CI value of z=				1.6449
margin of error E=z*std error                            =				0.0155
lower confidence bound=sample proportion-margin of error				0.0936
Upper confidence bound=sample proportion+margin of error				0.1246