Question

Q-10 Four Bulbs of 75 W each are lighted for 15 hrs daily and five ceiling fans of 120 W each
are switched on for 8 hours daily.
Find the total units of electricity consumed in the month of February 2010.
Also find monthly bill for February 2010, if the cost is Rs. 7/- per unit.​

Answer 1

Given:-

→ Power of each bulb = 75 W

→ Power of each fan = 120 W

→ Time for which the bulbs are

operated = 15h/day

→ Time for which the fans are

operated = 8h/day

→ Cost of per unit = Rs.7

To find:-

→ Total units of electricity consumed in

the month of February 2010.

→ Monthly bill for February 2010.

Solution:-

We know that :-

Energy = Power × Time

Energy consumed by the bulbs in one day :-

= 75/1000 × 15 × 4

= 0.075 × 60

= 4.5 kWh

Energy consumed by the fans in one day :-

= 120/1000 × 8 × 5

= 0.12 × 40

= 4.8 kWh

_______________________________

Since, 2010 was not a leap year, thus 28 days were there in the month.

Total energy consumed by the bulbs and the fans in Feb 2010 :-

= (4.5 + 4.8) × 28

= 9.3 × 28

= 260.4 kWh

Now, monthly bill for the month :-

= 260.4 × 7

= Rs.1822.80

________________________________

Thus :-

• Total units of energy consumed in

February 2010 is 260.4 .

• Monthly bill is Rs.1822.80