Thread: Probablity Question? Choosing bills?

Out of 10 $20 bills, 2 are counterfeit, 6 bills are chosen at random. What is the probability that both counterfeit bills are chosen?

--my attempt--

C(10,6)/(C(6,2) *C(10,2))

Is this correct? I am not sure.

Thanks

Originally Posted by blackZ

Out of 10 $20 bills, 2 are counterfeit, 6 bills are chosen at random. What is the probability that both counterfeit bills are chosen?

Your notion is off base.
Standard notation is , n things choosing k.

So the answer will be .

Hello, blackZ!

Out of ten $20 bills, two are counterfeit.
Six bills are chosen at random.
What is the probability that both counterfeit bills are chosen?

There are: possible outcomes.

There are: 2 fake and 8 real bills.
We want: 2 fake and 4 real bills.

There are: . ways.