Question

The lengths of pregnancies in a small rural village are normally distributed with a mean of 260 days and a standard deviation of 17 days.

In what range would you expect to find the middle 98% of most pregnancies?

Answer 1

Rounded to the nearest integer the range would be:

220 < x < 300

Explanation:

For a 98%the Z-score is 2.326

then you calculate the interval using:

Mean +/- Z * standard deviation

In our case:

260 +/- 2.326 * 17 = between 220.458 and 299.542

Rounded to the nearest integer would be:

220 < x < 300