How to read a joint discrete table?

[JackLee]

Homework Statement

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Given a group of 100 married couples, let X1 be the number of sons and X2 the number of daughters the couple has.

P(X1 = 0, X2 = 2) = f(0, 2) = 8 /100 = 0.08


2. Homework Equations

The Attempt at a Solution

I tried to look for a similar example online, I found this one:

for this one, there is 1 female and 37 male in math department and the table is making sense.

But for the first table, I am assuming the subscripts 0,1,2 are the number of boys/girls.
So I read the first column as: there are 6 married couple that have 0 boy and 0 girl, there are 15 couples with 0 boy and 2 girls. So P(X1 = 0, X2 = 2) = f(0, 2) should = 15/100, which is different from the given solution. Or was it a typo that X1 was meant to be the number of girls? then f(0, 2) = 8 /100 would makes sense.

I am so confused, please help

 

[andrewkirk]

Your answer is correct, based on how you wrote the question. I suspect they just wrote the question wrong, and meant X1 to be the number of girls and X2 the number of boys.

 

[JackLee]

Your answer is correct, based on how you wrote the question. I suspect they just wrote the question wrong, and meant X1 to be the number of girls and X2 the number of boys.

Thank you! yeah it's from my professor's power point, I think power points are prone to typos..I should have known better