Estimate the number of newborns whose weight was less than 5136 grams

Question

A study conducted by the Center for Population Economics at the University of Chicago studied the birth weights of 797 babies born in New York. The mean weight was 3464 grams with a standard deviation of 836

 grams. Assume that birth weight data are approximately bell-shaped

Answer 1

HI Amber,

Since it's bell-shaped, we can approximate it as a normal distribution. Our z-score is:

Z=(x-µ)/σ

=(5136-3464)/836=2

Using the z score distribution table (left of z score since they want "less than" the value of interest) or the 66-99-99.7 rule,

P=0.9772

Lastly, multiply this by 797:

779 newborns.



I hope this helps!