A plant is producing 10.000ty of a product. The overall yield is 70 per cent, on a mass basis ( kg of product per kg raw material). The raw material costs ElO/t, and the product sells for 235/t. A process modification has been devised that will increase the yield to 75 per cent. The additional investment required is 635.000 , and the additional operating costs are negligible. Is the modification worth making