A box contains marbles: 3 red, 6 blue, 7 yellow, and 4 purple. How many purple marbles should be added so that p(choosing a purple) becomes 0.9?
A box contains marbles: 3 red, 6 blue, 7 yellow, and 4 purple. How many purple marbles should be added so that p(choosing a purple) becomes 0.9?