Question

The lengths of pregnancies in a small rural village are normally distributed with a mean of 264.1 days and a standard deviation of 12.9 days. In what range would you expect to find the middle 95% of most pregnancies

Answer 1

The range of the 95% data (X) = 238.3 days < X < 289.9 days

Explanation:

Given;

mean of the normal distribution, m = 264.1 days

standard deviation, d = 12.9 days

between two standard deviation below and above the mean is 96% of all the data.

two standard deviation below the mean = m - 2d

= 264.1 - 2(12.9)

= 238.3 days

two standard deviation above the mean = m + 2d

= 264.1 + 2(12.9)

= 289.9 days

The middle of the 95% of most pregnancies would be found in the following range;

238.3 days < X < 289.9 days