Practice!

Sample Problem

There are 180 ping-pong balls in a bag. 40% of them are white and the remaining are yellow. If 50% of the white balls were taken out of the bag, what will be the new percentage of white balls in the bag?

%

Solution

Use the formula: Part = Whole × Percentage

The number of white balls: 180 × 40% = 72

The number of white balls taken out: 72 × 50% = 36

Then, the remaining white balls: 72 – 36 = 36

The total balls left: 180 – 36 = 144

Thus, the new percentage: 36 ÷ 144 = 0.25 = 25%