The average (arithmetic mean) weight of 5 boxes is 40 kg. If two more boxes, weighing 35 kg and 45 kg, are added to the group, what is the new average weight of all the boxes?

✓ Correct Answer: Option B

The initial total weight of 5 boxes is 5 * 40 kg = 200 kg. The weight of the two added boxes is 35 kg + 45 kg = 80 kg. The new total weight is 200 kg + 80 kg = 280 kg. The new total number of boxes is 5 + 2 = 7. The new average weight is 280 kg / 7 boxes = 40 kg.