Question

The lengths of a particular​ animal's pregnancies are approximately normally​ distributed, with mean muequals271 days and standard deviation sigmaequals8 days. ​(a) What proportion of pregnancies lasts more than 283 ​days? ​(b) What proportion of pregnancies lasts between 269 and 275 ​days? ​(c) What is the probability that a randomly selected pregnancy lasts no more than 267 ​days? ​(d) A​ "very preterm" baby is one whose gestation period is less than 251 days. Are very preterm babies​ unusual? LOADING... Click the icon to view a table of areas under the normal curve. ​(a) The proportion of pregnancies that last more than 283 days is nothing. ​(Round to four decimal places as​ needed.) ​(b) The proportion of pregnancies that last between 269 and 275 days is nothing. ​(Round to four decimal places as​ needed.) ​(c) The probability that a randomly selected pregnancy lasts no more than 267 days is nothing. ​(Round to four decimal places as​ needed.) ​(d) A​ "very preterm" baby is one whose gestation period is less than 251 days. Are very preterm babies​ unusual? The probability of this event is nothing​, so it ▼ would not would be unusual because the probability is ▼ greater less than

Answer 1

Population mean

Population standard deviation

Formula to calculate z-score:

Let X be the length of particular​ animal's pregnancies

Ans a)

ans.

Explanation: we can find probability using excel function:=NORM.S.DIST(1.5,TRUE) = 0.9332

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Ans b)

ans.

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Ans c)

ans.

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Ans d)

ans

Yes, very preterm babies​ unusual because probability is less than 0.05