Question

The lengths of a particular​ animal's pregnancies are approximately normally​ distributed, with mean mu equals256 days and standard deviation sigma equals8 days.

​(a) What proportion of pregnancies lasts more than 258 ​days?

​(b) What proportion of pregnancies lasts between 242 and 260 ​days?

​(c) What is the probability that a randomly selected pregnancy lasts no more than 252 ​days?

​(d) A​ "very preterm" baby is one whose gestation period is less than 236 days. Are very preterm babies​ unusual?

Answer 1

Given data :

Mean=256

std dev=8

The lengths of a particular​ animal's pregnancies are approximately normally​ distributed

​(a) What proportion of pregnancies lasts more than 258 ​days?

P(X>258)

(Using Std Normal table)

(b) What proportion of pregnancies lasts between 242 and 260 ​days?

  

(Using Std Normal table)

c) What is the probability that a randomly selected pregnancy lasts no more than 252 ​days?

   (Using Std Normal table)

d) A​ "very preterm" baby is one whose gestation period is less than 236 days. Are very preterm babies​ unusual?

  

  

  (Using Std Normal table)

0.0062 which is unusual because it is less than 0.05