A 12 hp motor has to be operated 8 hours per day. How much will it cost at the rate of 50 paisa per kWh in 10 days

given that an electric motor is of power

P = 12 hp                                 1 hp = 746 watt

$\text{P}=\text{12}\times \text{746 watt}$

When it is operated for 8 hours a day and for 10 days.

Number of kilo watt hour consumed $=\frac{12\times 746\times 80}{1000}\text{kwh}$ 

If cost of 1 kwh is 50 paisa $=\frac{1}{2}\text{\hspace{0.17em}Rupee}$

The cost of utilizing electric power.

Total cost = Number of kwh consumed × cost of 1 kwh

$=\frac{12\times 746\times 8\times 10}{1000}\times \frac{1}{2}\Rightarrow 358.08Rs.$