1. The following shows the demands andmarginal revenue in two markets (D1 and MR1, and D2 and MR2) for a price discriminating firm along with total demand, DT, marginal revenue, MRT, and marginal cost MC.

450 D2 400 MR2 MC 350 300 DT D1 ... ................. MRT 250 MR1 ...... ......................... 200 150 .................................................. MC 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 . . D1 - - - MR1 - D2 - - MR2 ......... MRT DT - MC