Give your answers as decimals, to three places

Question

Out of 600 people sampled, 306 had kids. Based on this, construct a 95% confidence interval for the true population proportion of people with kids.

Answer 1

95% confidence means z = 1.96

p = 306/600 = 0.51 > 1/2

1.96 * sqrt( 0.51 (1- 0.51) / 600 )

1.96 * sqrt( 0.51 * 0.49 / 600 )

1.96 * 0.02040833163195855....=

0.04+

The real proportion lies in the range ( 0.47-, 0.55+) with 95% certainty