The Wholesale Price Index (WPI) was main index for measurement of inflation in India till April 2014 when RBI adopted new Consumer Price Index (CPI) as the key measure of inflation.
If hiring an extra worker increases a factory's output from 1000 to 1200 units per day, but the factory has to reduce the price of its product from Rs. 25 to Rs. 24 per unit to sell the additional output, the marginal revenue product of the last worker is