SOLUTION: There are 5 red and 7 black identical balls in a bag. Peter picks two balls from the bag at random one after the other without replacement. Find the probability that he picked
(a)
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(a)
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Question 1124683: There are 5 red and 7 black identical balls in a bag. Peter picks two balls from the bag at random one after the other without replacement. Find the probability that he picked
(a) two balls that were of the same colour.
(b) at least one red. Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! two of same color means both red or both black
for red (5/12)(4/11) or 20/132
for black (7/12)(6/11) or 42/132
Those probabilities don't overlap, so the combined is 62/132 or 0.47
At least one red is 1- probability of no red
That probability is 42/132 from above, so the answer is 90/132 or 0.68
