Question

There were 2,074,000 baby girl and 2,173,000 baby boy born. We often assume that the

probability of having a boy or a girl is 0.5 because of the chromosomal determination of sex in

humans. Is there reason to think that the sex ratio in the United States favor more baby boys?

To answer this question, find the probability that an equal chance of getting a boy would give

2,173,000 boys or more in 4,247,000. What do you conclude?

Answer 1

We will use normal approximation to binomial distribution.

where n=4247000 and p=0.5

np=2123500

np(1-p)=1061750

Now we are interested in calculating

(continuity correction)

An equal chance giving more than 2173000 boys is almost negligible and equal to zero.