A cardboard box has a length of 3 feet, height of 2(1/2) feet, and depth of 2 feet. If the length and depth are doubled, by what percent does the volume of the box change?

The volume of the original box is 3*2(1/2)*2=15. The volume of the box with the length and depth doubled is 6*2(1/2)*4=60. The amount of change in volume is 60 – 15 =45. The percent change is the amount of change in volume divided by the original volume: 45/15 × 100% = 300%.