A can build a wall in 30 days, while B alone can build it in 40 days. If they build it together and get a payment of Rs. 7000, what is B's share?
Answer: B
The ratio of their efficiencies is inversely proportional to the time they take. Ratio of time A:B = 30:40 = 3:4. Ratio of efficiency A:B = 4:3. The wages will be shared in the ratio of efficiency. B's share = \(\frac{3}{4+3} \times 7000 = \frac{3}{7} \times 7000 = 3000\). B's share is Rs. 3000.