Assume you have 6 dimes and 5 quarters (all distinct), and you select 5 coins.
Total ways selection can be made= 462
How many ways can the selection be made so that at least 4 coins are dimes?______________

Question

Assume you have 6 dimes and 5 quarters (all distinct), and you select 5 coins.
Total ways selection can be made= 462
How many ways can the selection be made so that at least 4 coins are dimes?______________

anonymous · Answer

(6C4)+(7C1)

anonymous · Answer

6x5x4x3
--------  = 15 +7= 22
4x3x2x1  

Is that right?

anonymous · Answer

that didnt work

anonymous · Answer

6*5*4*3*2*1        7*6*5*4*3*2*1
------------  +  --------------
4*3*2*1*2*1         1*6*5*4*3*2*1

directrix · Answer

Two separate cases: That would be the sum of the numbers of ways to choose exactly 4 dimes and then exactly 5 dimes.. C(6,4) times C(5,1) + C(6,5) times C(5, 0)  =  81.

directrix · Answer

I included the case of 6 dimes and messed up the first time.

anonymous · Answer

That did it direct.... awesome man

anonymous · Answer

it is hard for me to id the cases in a lot of these

directrix · Answer

It is tricky.

anonymous · Answer

1 more i couldn't do from that section i am going to post....
thank you so much

directrix · Answer

Ok, I'll look for it.