# Math Help - Combinations problem

1. ## Combinations problem

There are 3 boys and 2 girls from city X and 2 boys and 3 girls from city Y ready to be married.If a person cannot marry someone from own city.....how many distinct weddings are possible.....Please Help.....Do give the formula

2. Originally Posted by anshulbshah
There are 3 boys and 2 girls from city X and 2 boys and 3 girls from city Y ready to be married.If a person cannot marry someone from own city.....how many distinct weddings are possible.....Please Help.....Do give the formula
I'm also going to assume that boys must marry girls and vice-versa!

The 3 boys from city X must marry the 3 girls from city Y (nice how that works out!) How many different ways can that be done? The two boys from city Y must marry the 2 girls from city X. How many ways can that be done? And now that you have those two numbers, how do you combine them to answer the question.

This, as all such problems, is an application of the "fundamental principle of counting": if A can happen in n ways and B can happen in m ways, then A and B can happen together in mn ways.

3. Originally Posted by HallsofIvy
I'm also going to assume that boys must marry girls and vice-versa!

The 3 boys from city X must marry the 3 girls from city Y (nice how that works out!) How many different ways can that be done? The two boys from city Y must marry the 2 girls from city X. How many ways can that be done? And now that you have those two numbers, how do you combine them to answer the question.

This, as all such problems, is an application of the "fundamental principle of counting": if A can happen in n ways and B can happen in m ways, then A and B can happen together in mn ways.
Thanks first of all....
Could u please tell me the final answer ... As the answer in the the book (frm. which i got the question) is 13 and 13 doesnt have any factors.....

Thnx..
anshulbshah

4. Originally Posted by anshulbshah
Thanks first of all....
Could u please tell me the final answer ... As the answer in the the book (frm. which i got the question) is 13 and 13 doesnt have any factors.....

Thnx..
anshulbshah

And yes....this isnt a University Math problem.....the book frm which i got the q is a Grade 9 book

Thnx...once again

5. Originally Posted by anshulbshah
Thanks first of all....
Could u please tell me the final answer ... As the answer in the the book (frm. which i got the question) is 13 and 13 doesnt have any factors.....
$[3\times 3] + [2\times 2]=13$

6. [GVIDEO][/GVIDEO]
Originally Posted by Plato
$[3\times 3] + [2\times 2]=13$
Thnx..... Plato.....
But wanted to ask ..... is this not related to permutation or combinations and the formula of N!/(n-r)! * r!

anshulbshah

7. Originally Posted by anshulbshah
But wanted to ask ..... is this not related to permutation or combinations and the formula of N!/(n-r)! * r!
It is not related to either of those.
It is all about the cross product (ordered pairs)
The males from X with females from Y plus males from Y with females from X.