In a bag with 20 marbles, five of them are blue. How many blue marbles must be added to the bag so that the probability of selecting a blue marble at random is $\frac{1}{2}$?
Question:
In a bag with 20 marbles, five of them are blue. How many blue marbles must be added to the bag so that the probability of selecting a blue marble at random is $\frac{1}{2}$?
Answer:
Let's think step by step.

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In a bag with 20 marbles, five of them are blue. How many blue marbles must be added to the bag so that the probability of selecting a blue marble at random is $\frac{1}{2}$?
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