If a 60w incandescent bulb is replaced by a 15w fluorescent bulb, how much less electricity energy (in kilowat*hours) is consumed in a week by the fluorescent bulb, operating for 12 h each day?

3.78 kWh

Explanation:

Power of incandescent bulb = 60 W = 0.06 kW

Power of fluorescent bulb = 15 W = 0.015 kW

Number of hours in a week if each day the light is turned on 12 hours

12×7 = 84 hours

Difference in power

0.06-0.015 = 0.045 kW

Multiplying with the number of hours

Hence, the fluorescent bulb will consume 3.78 kWh less electricity energy than the incandescent bulb.