Probability question: Out of 50 parts, 10 are defective. If you choose 1 at random, what is probability 1st choice is defective? What is probability 1st and 2nd choice defective? What is probability 2nd choice defective, given 1st choice defective? What is probability second choice defective?

Question

anonymous · Answer

I would like to check my answers....

anonymous · Answer

Probability 1st choice defective = 10/50 = 1/5
Probability 1st and 2nd choices defective = (1/5)(9/49)
Probability 2nd defective given first is defective = 9/49

anonymous · Answer

Am I on the right track??

anonymous · Answer

Oh yes! Good job!

anonymous · Answer

Really?

anonymous · Answer

Yep!
However, the problem has a bit of ambiguity. Do you take the defective part off once you select it or not?
It's not your fault, it's the problem's fault :)

anonymous · Answer

It was specified that you take if off and don't replenish (; Sorry I should have specified.