Question

An electric lamp is marked 60 W, 230 V. The cost of 1 kilowatt hour of power is Rs. 1.25. The cost of using this lamp for 8 hours is

• A. Rs. 1.20
• B. Rs. 4.00
• C. Rs. 0.25
• D. Rs. 0.60

Answer 1

Answer: (D)

Rs. 0.60

Answer 2

By using consumed unit (n) or KWH

$= \frac{\text{Total Watt} \times \text{ Total time}}{\text{1000}}$ ⇒ $n = \frac{60 \times 8}{1000} = \frac{12}{25}$

So cost $= \frac{12}{25} \times 1.25 = 0.60Rs$