Question

The length of human pregnancies from conception to birth varies according to a distribution that is approximately Normal with mean 266 days and standard deviation 16 days. What percent of pregnancies last between 240 and 270 days (roughly between 8 months and 9 months)?

Answer 1

Answer:

0.5466

Step-by-step explanation:

Given that the  length of human pregnancies from conception to birth varies according to a distribution that is approximately Normal with mean 266 days and standard deviation 16 days.

Let X be the length of pregnancies

X is N(266,16)

To find out the probability that pregnancies last between 240 and 270 days (roughly between 8 months and 9 months)

P(240<x<270)

convert each into Z score as $z=\frac{x-266}{16}$

x=240 means Z = -1.625

x=270 means z=0.25

Required prob

= $P(-1.625<Z<0.25)\\= 0.5466$