The selling price (SP) is calculated using the formula:
\[SP = CP \times \left(1 + \frac{\text{Profit \%}}{100} \right)\]\[ SP = 3,924 \times \left(1 + \frac{25}{100} \right) \]
\[ SP = 3,924 \times 1.25 \]
\[ SP = 4,905 \]
Thus, the selling price is Rs 4,905 (Option B).
An electricity utility company charges ₹7 per kWh. If a 40-watt desk light is left on for 10 hours each night for 180 days, what would be the cost of energy consumption? If the desk light is on for 2 more hours each night for the 180 days, what would be the percentage-increase in the cost of energy consumption?