help prob?

[lostwithmath]

Im trying to figure out how to estimate the probability a baby will be born female? Using data from a year in last 15 years.

The information I got from research is born 2000:

143 million females
138 million males

total population for 2000 is 276,059,000

I have taken 143 mil/ 276059000 = 0.518
I have taken 138 mil/ 276059000 = 0.49989

Do I need to do something else or is my probability for a femal being born in 2000 0.518.

 

[soroban]

Hello, lostwithmath!

Im trying to figure out how to estimate the probability a baby will be born female,
using data from a year in last 15 years.

The information I got from research is born 2000:

. . 143 million females
. . 138 million males

. . total population for 2000 is: 276,059,000 . . . . irrelevant!

There were 281 million babies born in 2000.

Among them were 143 million females and 138 million males.

. . P(female) .= .143m/281m .= .50.89%
. . . .P(male) .= .138m/281m .= .49.11%

[You should have become suspicious
. . when your two probabilities didn't add up to 100%.]