There are five boxes in cargo hold. The weight of the first box is 200 kg and the weight of the second box is 20% higher than the weight of the third box, whose weight is 25% higher than the first box's weight. The fourth box at 350 kg is 30% lighter than the fifth box. Find the difference in the average weight of the four heaviest boxes and the four lightest boxes. Choose the correct choice
A) 51.5 kg
B) 75 kg
C) 37.5 kg
D) 112.5 kg
E) None of these
Solution: The weight of boxes is;   1st box = 200 kg;   3rd box = 250 kg;   2nd box = 300kg;   4th box = 350 kg;   5th box = 500 kg.   Hence, difference between heavier 4 and lighter 4 is 300.   Hence, difference in average is 75.   Answer: Option 75 kg
<result>B</result>
There are five boxes in cargo hold. The weight of the first box is 200 kg and the weight of the second box is 20% higher than the weight of the third box, whose weight is 25% higher than the first box's weight. The fourth box at 350 kg is 30% lighter than the fifth box. Find the difference in the average weight of the four heaviest boxes and the four lightest boxes.