Question

A $12\, HP$ motor has to be operated $8\, h /$ day. How much will it cost at the rate of $50$ paise/kWh in 10 days?

• A. Rs 350
• B. Rs 358
• C. Rs 375
• D. Rs 397

Answer 1

The Correct Option is B

If a motor of $12\, HP$ works for $10$ days at the rate of $8\, h /$ day then Energy consumption power $\times$ time $=12 \times 746 \frac{ J }{ s } \times(80 \times 60 \times 60) s$ $=12 \times 746 \times 80 \times 60 \times 60\, J$ $=2.5 \times 10^{9} J$ Rate of energy $=50 \frac{\text { Paise }}{ kWh }$ $\because 3.6 \times 10^{6} J$ energy cost $=$ Rs $0.5$ $\therefore 2.5 \times 10^{9} J$ energy cost $=\frac{2.5 \times 10^{9}}{2 \times 3.6 \times 10^{6}}$ $=$ Rs $358$