Using x skilled workers and y unskilled workers, a manufacturer can produce Q(x, y) = 60x^1/3y^2/3 units per day. Currently the manufacturer employs 10 skilled workers and 40 unskilled workers and is planning to hire 1 additional skilled worker. Use calculus to estimate the corresponding change that the manufacturer should make in the level of unskilled labor so that the total output will remain the same.