## mathmath333 one year ago Counting question

1. mathmath333

\large \color{black}{\begin{align} & \normalsize \text{The number of ways of dividing 20 different balloons }\hspace{.33em}\\~\\ & \normalsize \text{in two groups containing 11 and 9 balloons is ? }\hspace{.33em}\\~\\ \end{align}}

2. ganeshie8

you choose 11 balloons for the first group the other group is automatically determined

3. anonymous

i agree with ganeshie8

4. mathmath333

5. ganeshie8

Yes, notice, that also equals 20C9 and agrees with our present problem that you could have chosen the balloons for the second group first

6. mathmath333

7. ganeshie8

20C11 looks correct to me! textbook answer could be wrong, doesn't make sense to m

8. mathmath333

but 9C9=1

9. ganeshie8

lol okay i read it as 20C11*20C9 for some reason