- Step 1: Cost price = Rs. 400, Profit = 25%.
- Step 2: Selling price = Cost price $\times (1 + \frac{\text{Profit}%}{100}) = 400 \times 1.25 = 500$.
- Step 3: Verify: Profit = $500 - 400 = 100$, which is $25%$ of 400.
- Step 4: Check options: Option (3) is Rs. 500, correct.