Question 1000580: Dear tutor,
Please help me with this question.
A jar contains 10 blue marbles, 5 red marbles, 4 green marbles, and 1 yellow marble. Two marbles are chosen (without replacement).
(a) What is the probability that one will be green and the other red?
Total is 20. P(green)=4/20 P(red)=5/19 (total is 19 because is says without replacement) 4/20 x 5/19 = 0.0526. but the answer is 2/19= 0.105
I am not sure what I am missing here...Thank you in advance....
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! a) There are 190 ways to choose 2 marbles, that is 20 marbles taken 2 at a time is 20! / (2! * (20 - 2)!) = (20 * 19) / 2 = 190,
there are 5 * 4 possible sets that include 1 green and 1 red, therefore
Probability(1 green, 1 red) = ((5*4) / 190) = (20 / 190) = 2 / 19
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