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

Gabrielle Watson · Accepted Answer

Final Answer : C, Explanation :  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 = 1.14Using 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.

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