anonymous 3 years ago How many different 12-member juries can be chosen from a pool of 40 people? I really can't understand this.

1. .Sam.

40C12?

2. mathslover

And : $$\large ^n C_r = \cfrac{n!}{r! (n-r)!}$$

3. mathslover

@Haruhi , can you solve it now?

4. anonymous

not really. I've been trying to solve it that way all this time. I'm getting weird results.

5. .Sam.

From $\large ^n C_r = \cfrac{n!}{r! (n-r)!} = \frac{40!}{12!(40-12)!} = \frac{40 \times 39 \times 38 \times...}{(12 \times 11 \times 10 \times ...)(28 \times 27 \times 26 \times ...)}$

6. .Sam.

Or just use a calculator

7. .Sam.

What do you get?

8. anonymous

I get 1.5186643e+48 (whatever that means) and my options are a) 3,586,853,480 b) 4,586,853,480 c) 5,586,853,480 d) 6,586,853,480

9. .Sam.

Lol you should get 5,586,853,480 check your calculator

10. Zarkon

type "calculate 40 choose 12" into google

11. .Sam.

Ahh

12. Zarkon

it will take "40 choose 12" and give the answer

13. anonymous

I think we don't have Google in the exam!?

14. anonymous

Ok..... still confused. How can a calculator be wrong lol what the hell am I doing

15. anonymous

Try:$\frac{40!}{(12!(40-12)!)}$

16. anonymous

That is wrong all of you I think its 12 times 40 its simple probability i think

17. anonymous

No nevermind

18. anonymous

Its c

19. anonymous

It's the right answer, yeah. But it's damn confusing having to work with numbers like 815,915,279,999,999,744,392,488,672,368,848,648,400,776,424,296 -_- so I must've made a mistake at some point.

20. anonymous

please dont say dam on a post there are 7th graders in geometry and algebra 2 like me who don't like that

21. anonymous

ok... >_>

22. anonymous

What is that supposed to mean

23. anonymous

weirdos