Question

If an electric bulb, of rating 60 watts, is operated for 10 hrs everyday. The cost of electricity is charged as 8 rupees per unit. What is the cost of lighting the bulb for 1 month?

• A. Rs 110
• B. Rs 220
• C. Rs 200
• D. Rs 144

Answer 1

The correct option is D Rs 144

Given:
Amount of time the bulb glows everyday = 10 hrs
In 30 days the bulb glows for = $30\times 10=300hrs$;

The bulb consumes 60 watts for 10 hrs every day, therefore the amount of electricity consumed in one day is $60\times 10=600watt-hourorWh$
in kWh $\to 1kWh=1000Wh$
so, 600 Wh = $\frac{600}{1000}=0.6kWh$
Bulb consumes 0.6 kWh everyday
In 30 days it will consume $30\times 0.6=18kWh$
Since 1 unit of electricity is 1kWh
$\therefore$ The bulb consumes 18 kWh or 18 units of electricity in 30 days or a month.
Cost of 1 unit of electricity = Rs 8
Cost of lighting the bulb for every day for one month will be $8\times 18=Rs144$