A bag contains 6 red marbles, 4 blue marbles, 7 green marbles, and 3 yellow marbles. A marble is drawn from the bag and is not replaced. Then a second marble is drawn. What is the probability that both marbles drawn were yellow?

Question

anonymous · Answer

9/400

9/380

3/200

3/190

johnweldon1993 · Answer

Well first...there were 20 marbles in the beginning...and 1 was chosen..so that probability of it being yellow..was

3 yellow marbles
-------------- = 3/20 chance
20 total marbles

Now...it wasn't replaced so there are only 19 marbles left..we still want a yellow...so the chance now is 

3 yellow marbles
--------------- = 3/19 chance
19 total marbles

To find the chance of those both happening...you multiply the 2 probabilities...

3         3          9
--  x  ---  =  ----
20       19       380

anonymous · Answer

Thank you!!!

johnweldon1993 · Answer

Anytime! :)

anonymous · Answer

no answer is D

C(3,2) / C(20,2) = 3/190