6 girls are arranged into 2 rows. Given that each row contain at least 1 girl, find the number of the possible combination(s)
My solution: Using the concept of repeated combinations,
$_{2+4-1} C _{4} $
=$_5C_4$
=5
(The answer key says it is 2160, can someone please explain?)
They are considering different orders of girls to be different. You can imagine putting the girls in one row in $6!=720$ ways then choosing a point to split the rows in five ways. That would give $3600$ possibilities. They may be thinking that $ABC/DEF$ is the same as $DEF/ABC$ but that only deducts $360$ leaving $3240$. I can't get to $2160$.