Johnrohit wrote:In a bag of marbles, there are 3 red, 2 white, 5 blue. If bob takes 2 marbles out of the bag, What is the probability that he will have one white and one blue marble?(Assuming that Bob does not replace the marbles in the bag)
Alternate approach:
P = good/all.
All:
Number of ways to choose 2 marbles from 10 options = 10C2 = (10*9)/(2*1) = 45.
Good:
A good pair is composed of 1 white marble and 1 blue marble.
Number of options for the white marble = 2.
Number of options for the blue marble = 5.
To combine these options, we multiply:
2*5 = 10.
Thus:
P(1 white and 1 blue) = 10/45 = 2/9.
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