500
A bag contains 25 balloons: 15 red, 3 yellow, and 7 orange. How many of each color balloon would you need so that the probability of drawing a red balloon was 1/2?
What is Answers vary: add 1 yellow and 4 oranges, or 2 yellows and 3 oranges, or 4 yellows and 1 orange, or 3 yellows and 2 oranges, or 5 yellows, or 5 oranges (THE POINT IS THAT YOU ADD 5 MORE BALLOONS THAT ARE NOT RED, SO THAT YOU HAVE 15/30 FOR RED'S PROBABILITY)