Question

A large national company is considering negotiating cellular phone rates for its employees. the human resource department would like to estimate the proportion of its employee population who own an apple iphone. a random sample of size 250 is taken and 40% of the sample own and iphone.. the 95% confidence interval to estimate the population proportion is _______.?

Answer 1

Sample size=n=250
sample proportion=p=0.4
95% confidence interval so significance level α=1-0.95=0.05
So, α/2=0.025
z_( α/2)=1.960 (value taken from statistic z-table)
use formula;

p(+/-)z_(α/2)square root(p(1-p)/n)

(0.4-1.960 sq.root(0.4(1-0.4)/250), 0.4+1.960 sq.root(0.4(1-0.4)/250))
(-0.2073,0.4607) (estimation of population proportion)