Question

In a house 5 CF lamps each of 24 W works for a period of 5 hours and 2 fans of 80 W for 5 hours. What is the electric consumption in kWh for a month?

• A. 18 kWh
• B. 24 kWh
• C. 42 kWh
• D. 60 kWh

Answer 1

The correct option is C

42 kWh

Given: Number of CFL lamps = 5, time = 5 hours and Power of CFL (P) = 24 W
Also, number of fans = 2, time = 5 hours and power of fans = 80 W

One month's consumption of energy by CFL
= $\frac{Powerinwatt\times NumberofCFL\times Numberofworkinghours\times Numberofdays}{1000}$
= $\frac{24\times 5\times 5\times 30}{1000}$
= 18 kWh

One month's consumption of energy by fans
= $\frac{Powerinwatt\times Numberoffans\times Numberofworkinghours\times Numberofdays}{1000}$
= $\frac{80\times 2\times 5\times 30}{1000}$
= 24 kWh

Hence, one month's total consumption of energy = 18 + 24 = 42 kWh.