Find the indicated probability.
-The lengths of human pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days. What is the probability that a pregnancy lasts at least 300 days?
A) 0.4834
B) 0.0179
C) 0.9834
D) 0.0166

Question

Quizplus · Accepted Answer

To solve the problem, we use the z-score formula:

z = (x - mu) / sigma

where x is the value we're interested in (in this case, 300), mu is the mean (268), and sigma is the standard deviation (15).

Plugging in the numbers, we get:

z = (300 - 268) / 15 = 2.13333

Now we look up the probability corresponding to a z-score of 2.13333 in a standard normal distribution table. The probability is about 0.0166.

Therefore, the probability that a pregnancy lasts at least 300 days is 0.0166, or approximately 1.66%. This corresponds to answer choice D.

Find the Indicated Probability