ritind wrote:I dont understand why order is considered while taking out the probability.
In the problem above, there is a SINGLE EVENT: the selecting of two marbles.
We need to account for ALL OF THE WAYS that this single event could yield a white marble and a blue marble.
There are TWO WAYS that this single event could yield a favorable outcome:
Case 1: If the first marble selected is white, and the second marble selected is blue.
Case 2: If the first marble selected is blue, and the second marble selected is white.
The probability of a favorable outcome is THE SAME in each case: 1/9.
Thus, the probability that this SINGLE EVENT OF SELECTING TWO MARBLES will yield a white marble and a blue marble = 2 * 1/9 = 2/9.
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