The answer is nine over eleven (9/11).
There are in total 22 marbles:
4 blue + 5 yellow + 6 red + 2 green + 5 purple = 22 marbles
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If there are 4 blue marbles, there are 18 marbles that are not blue:
22 marbles - 4 blue marbles = 18 non-blue marbles
The probability of randomly selecting a marble that is not blue is 18 out of 22:
18/22 = 9/11
