## mathmath333 one year ago counting problem

1. mathmath333

que:- In how many ways can 4 red, 3 yellow and 2 green discs be arranged in a row if the discs of the same colour are indistinguishable ?

2. anonymous

4 x 3x 2

3. anonymous

so 24

4. anonymous

wait!!!!!!!!

5. mathmath333

6. anonymous

i knew it!!!!!!

7. anonymous

it didnt seem right lol

8. anonymous

how did u get that lol?

9. anonymous

@mathmath333

10. mathmath333

from back of the book

11. anonymous

lmao wow

12. anonymous

so u dont know how to do it?

13. mathmath333

yep

14. anonymous

u do or dont?

15. anonymous

lol this dude bocked me cause i fanned him

16. mathmath333

i am also struggling to understand the meaning of sentence "arranged in a row if the discs of the same colour are indistinguishable"

17. geerky42

This means you can't tell the difference between two discs of same color, so saying we have #1 green disc and #2 green disc. 1 2 in order is same as 2 1. As in there is only one way to arrange #1 and #2 disc.

18. mathmath333

ok i see the key meaning

19. IrishBoy123

4 red, 3 yellow and 2 green that's $$\large \frac{9!}{4! \ 3! \ 2!}$$

20. mathmath333

that equals 1260

21. mathmath333

thnx