A and B together can finish a work in 30 days. They worked for it for 20 days and then B left the work. The remaining work was done by A alone in 20 days more. In how many days can A alone finish the work?
If hiring an extra worker increases a brick making unit's output from 2000 to 2250 units per day, but the factory has to reduce the price of its brick from Rs 15 to Rs 14 per brick to sell the additional output, the marginal revenue product of the last worker is