In: Statistics and Probability
The weight of freshly born babies approximates a normal distribution. The average weight of all babies born is 7.5 lbs (pounds), with a standard deviation of 2.5 lbs.
What proportion of babies will be lighter than 12.1 lbs?
Solution:
Given: The weight of freshly born babies approximates a normal distribution with mean weight of all babies born is 7.5 lbs (pounds), with a standard deviation of 2.5 lbs.
that is: ,
We have to find:
P( babies will be lighter than 12.1 lbs)=...........?
That is find:
P( X < 12.1 ) =..............?
Find z score for x = 12.1
thus we get:
Look in z table for z = 1.8 and 0.04 and find corresponding area.
P( Z < 1.84 ) = 0.9671
thus
P( babies will be lighter than 12.1 lbs)= 0.9671