The lengths of a particular animal's pregnancies are approximately normally distributed, with mean μ-255 days and standard deviation σ = 12 days.
(a) What proportion of
pregnancies lasts more than 270 days?
(b) What proportion of pregnancies lasts between 249 and 261 days?
(c) What is the probability that a randomly selected pregnancy lasts no more than 237 days?
(d) A "very preterm baby is one whose gestation period is less than 225 days. Are very preterm babies unusual?
Click the icon to view a table of areas under the normal curve.
(a) The proportion of pregnancies that last more than 270 days is 0.1056
(Round to four decimal places as needed.)
(b) The proportion of pregnancies that last between 249 and 261 days is 0.3829.
(Round to four decimal places as needed.)
(c) The probability that a randomly selected pregnancy lasts no more than 237 days is 0.0668.
(Round to four decimal places as needed.)
(d) A "very preterm baby is one whose gestation period is less than 225 days. Are very preterm babies unusual?
The probability of this event is 0.0062, so it would be unusual because the probability is less
(Round to four decimal places as needed.)
than 0.05.