Marbles 4: Blue
There are 35 marbles in a bag. Of which 3 are white, 5 are blue, 8 are red, 9 are green and 10 are yellow. The marbles will be taken out at random until a blue marble is taken out.
How many marbles will need to be taken out at most, to guarantee that we will get a blue marble?
The answer is 31.
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1 solution
In the worst possible scenario, you pick every single marble but a blue one which would take 30 turns. On the 31st turn you would be guaranteed a blue marble because every other marble has already been picked.