They try to randomly check 10 boxes were missing some number of 200 pieces.They use to weigh each and compare the weightWith 40 boxes does not have separate, so we go to count again.
They took samples examined showed some 10 boxes with a total of 200 missing pieces they used to weigh each box then compares the weight with a weight of 40 boxes that were not so separate, so we can count again.
They try 10 random check box found that there are some boxes were not 200 pieces they use แต่ละกล่อง balance method and compare weight by 40 box weight not so isolated, so we go from the number again.