In: Statistics and Probability
Solution :
Given that,
a) Point estimate = sample proportion = = x / n = 135 / 160 = 0.844
1 - = 1 - 0.844 = 0.156
Z/2 = Z0.025 = 1.96
Margin of error = E = Z / 2 * (( * (1 - )) / n)
= 1.96 (((0.844 * 0.156) / 160)
= 0.056
A 95% confidence interval for population proportion p is ,
± E
= 0.844 ± 0.056
= ( 0.788, 0.900 )
b) margin of error = E = 0.05
sample size = n = (Z / 2 / E )2 * * (1 - )
= (1.96 / 0.05)2 * 0.844 * 0.156
= 202.32
sample size = n = 203