A bag contains a total of 20 batteries, of which six are defective. Selecting two at random, without replacement, determine the probability that none of the batteries you select are good.

Question

A bag contains a total of 20 batteries, of which six are defective.  Selecting two at random, without replacement, determine the probability that none of the batteries you select are good.

anonymous · Answer

Alright, let's do one at a time. What is the probability that the first one selected is defective?

anonymous · Answer

Well I have so far is 6/20 but fro there am lost

anonymous · Answer

That's a good start.
Now, after taking out the first one (no replacement, remember), how many defective batteries are left, and how many total batteries are left? 

That will determine the probability that the second one is defective too.

anonymous · Answer

ummm 5/19??? I feel lost

anonymous · Answer

Nope, you're right on track.

This is an AND situation, i.e. the first pick was defective AND the second one was also defective.

In an AND situation, you multiply the two probabilities together.

anonymous · Answer

so 6/20*5/19, am I right?

anonymous · Answer

That'll do it.

anonymous · Answer

so I will multiply that and that will be my answer

anonymous · Answer

Yep. It'll also depend on how you want to express it: as a fraction, as a decimal, a percentage, etc.

anonymous · Answer

oh ok, I appreciate all your help...I'm a fan lol, be blessed

anonymous · Answer

70%

anonymous · Answer

^ ? 

"70%" @derk25heil ?

What does that mean?