Question

A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 520 babies were​ born, and 286 of them were girls. Use the sample data to construct a 99​% confidence interval estimate of the percentage of girls born. Based on the​ result, does the method appear to be​ effective?

< p <

Does the method appear to be​ effective?

Answer 1

Sample proportion = 286 / 520 = 0.55

99% confidence interval for p is

- Z/2 * sqrt [ ( 1 - ) / n ] < p < + Z/2 * sqrt [ ( 1 - ) / n ]

0.55 - 2.5758 * sqrt [ 0.55 ( 1 - 0.55) / 520] < p < 0.55 + 2.5758 * sqrt [ 0.55 ( 1 - 0.55) / 520]

0.494 < p < 0.606

Since 0.50 contained in confidence interval, this method does not appear to be effective.