The weights of 4 boxes are 70, 100, 20 and 40 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes?

• 230

• 190

• 160

• 200

D.

200

Total weight of 4 boxes = (70 + 100 + 20 + 40)kg = 230 kg
Now, check the combinations:
   Total weight  - weight of last box = (230 - 40) = 190 kg
   Total weight - weight of first box  = (230 - 70) = 160 kg
∴  200 cannot be the total weight as per the combinations.