A bag contains a total of 14 batteries, of which five are defective. Selecting two at random, without replacement, determine the probability that none of the batteries you select are good.

1/2
1/7
10/91
5/14

Question

A bag contains a total of 14 batteries, of which five are defective.  Selecting two at random, without replacement, determine the probability that none of the batteries you select are good.
  
       1/2
       1/7
       10/91
       5/14

anonymous · Answer

Looks like it's the 3rd one:

(5/14)*(4/13) = 10/91

anonymous · Answer

There are 5 defective ones to choose at first.
So assuming you pick a bad one, there are 4 defective ones left out of a total of 13.
The chance of both happening is the product of the individuals:
$$\frac{5}{14}*\frac{4}{13} = \frac{10}{91}$$