## anonymous 5 years ago nCk= The combinations of n taken k at a time. which of the following is equal to 11C8? a) 11!/3! b) 11!/11!8! c) 11!/8!3! d) 11!/8!

1. anonymous

Is it a..?

2. anonymous

no c

3. anonymous

nCr = n!/r!(n-r)!

4. anonymous

c is the right choice

5. anonymous

nPk = n!/(n-k)1

6. anonymous

right

7. anonymous

dont be confused between permutations and combination , both are different

8. anonymous

yep agreed :D

9. anonymous

I'm confused between the two formulas and two answers

10. anonymous

11C8= 11! ----- 8!*3!

11. anonymous

i have a way combination : we only select the items permutation: we select and we also arrange the items

12. anonymous

umm .. sorry that will be when u do problems of probability

13. anonymous

but metarock ur definition is right

14. anonymous

ya but chizzle was confused in the formulas , a different context though

15. anonymous

Ah, just found a way to remember (P)ermutation ... (P)osition matters both begin with P

16. anonymous

(C)ombination and (C)ounting (or selecting) ;-)

17. anonymous

So then it is 11!/8!3! ?

18. anonymous

yups

19. anonymous

Okay thank you all for the help/formulas/and differences between them

20. anonymous

ur welcome