There are 5 red marbles, 3 blue marbles and 2 greeen marbles. If a user chooses to use two marbles,what is the probability that the two marbles will be a different color?
The approach that I used was:
I added the results and came up with 9/45 then when that is simplified I get 1/5.
1-1/5=4/5 this is the result I got but the answer says 31/45 after using the combination approach.
Shouldn't the two approaches bring about the same result? Or did I do something wrong?
You did everything right except the addition: 2/9+1/15+1/45=10/45+3/45+1/45=14/45 (not 9/45) --> 1-14/45=31/45.
Unbelievable! I can't believe I did that... Thanks Bunuel! I don't know what's wrong with me..