Problem:
A large urn contains 100 balls, of which are red and the rest are blue. How many of the blue balls must be removed so that the percentage of red balls in the urn will be ? (No red balls are to be removed.)
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Solution:
There are currently 36 red balls in the urn. In order for the red balls to represent of the balls in the urn after some blue balls are removed, there must be balls left in the urn. This requires that blue balls be removed.
The problems on this page are the property of the MAA's American Mathematics Competitions