David invested certain amount in three different schemes `A ,\ B` and `C` with the rate of interest 10% p.a., 12% p.a. and 15% p.a. respectively. If the total interest accrued in one year was Rs 3200 and the amount invested in Scheme `C` was 150% of the amount invested in Scheme `A` and 240% of the amount invested in Scheme `B` , what was the amount invested in Scheme `B` ? (a) Rs 5000 (b) Rs 6500 (c) Rs 8000 (d) Cannot be determined