SOLUTION: The lengths of a particular​ animal's pregnancies are approximately normally​ distributed, with mean muequals250 days and standard deviation sigmaequals12 days. ​(a) What pr

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Question 1161797: The lengths of a particular​ animal's pregnancies are approximately normally​ distributed, with mean muequals250 days and standard deviation sigmaequals12 days.
​(a) What proportion of pregnancies lasts more than 256 ​days?
​(b) What proportion of pregnancies lasts between 232 and 259 ​days?
​(c) What is the probability that a randomly selected pregnancy lasts no more than 244 ​days?
​(d) A​ "very preterm" baby is one whose gestation period is less than 223 days. Are very preterm babies​ unusual?

Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
a. z is more than 6/12 or 1/2.That probability is 0.3085
b. z is between -1.5 and +0.75 with probability of 0.7066
c. z is less than -0.5, and since the curve is symmetrical, that is the same answer as a or 0.3085 probability
d. z is less than -2.25 or 0.0122. Uncommon but given the number of babies born is uncommon for sure.

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