Birth weights of babies born to full-term pregnancies follow roughly a Normal distribution.At Meadowbrook Hospital,the mean weight of babies born to full-term pregnancies is 7 pounds with a standard deviation of 14 ounces (1 pound = 16 ounces). Rachel is one of Dr.Watts's patients.Rachel had an ultrasound 3 weeks ago and the doctors established that the baby already weighed 7 pounds at that point.She is about to deliver her baby (full term).What is the probability that the baby will be more than 8 pounds?
A)0.0065
B)0.1265
C)0.2531
D)0.4858

Question

Quizplus · Accepted Answer

First, we need to convert the weights to the same unit of measure. 7 pounds are equivalent to 112 ounces (7 x 16). 
To find the probability that the baby will be more than 8 pounds (128 ounces), we need to find the z-score and then look it up in the Normal distribution table.

z = (128 - 112) / 14 = 1.14

Using the Normal distribution table, the probability of a z-score of 1.14 or greater is 0.2531. Therefore, the probability that the baby will be more than 8 pounds is 0.2531 or 25.31%.

The best choice is C.

Birth Weights of Babies Born to Full-Term Pregnancies Follow Roughly