Question

In a sample of 210 adults, 195 had children. Construct a 90% confidence interval for the true population proportion of adults with children.

Give your answers as decimals, to three places

Answer 1

Solution :

Given that,

Point estimate = sample proportion = = x / n = 195 / 210 = 0.929

Z_/2 = 1.645

Margin of error = E = Z _{/ 2} * (( * (1 - )) / n)

= 1.645 * (((0.929 * 0.071) / 210)

= 0.030

A 90% confidence interval for population proportion p is ,

- E < p < + E

0.929 - 0.030 < p < 0.929 + 0.030

0.899 < p < 0.859

(0.899 , 0.859)