Question

There are 5 rooms in a house. Each room has a 100W bulb and a 40 W tube light. If every day the bulb is
used for 1 hour and tube light is used for 5 hours in each room then what will be the cost of total electric
energy consumed in 30 days when 1 unit of electric energy costs Rs. 2.5.​

Answer 1

Answer:

Cost of electric energy =Rs. 3.00×128.4=Rs.  385.20

Explanation:

ANSWER

Energy consumed by 4 tubelights per day, E  

tubelight

​  

=(4)(40)(5)=800 WH

Energy consumed by 3 fans per day, E  

fan

​  

=(3)(80)(12)=2880 WH

Energy consumed by television per day, E  

TV

​  

=(100)(6)=600 WH

Total energy consumed per day, E=E  

tubelight

​  

+E  

fan

​  

+E  

TV

​  

 

∴  E=800+2880+600=4280 WH =4.280  KWH per day

Total energy consumed in 30 days, E  

T

​  

=30×4.280=128.4  KWH

Cost of electric energy =Rs. 3.00×128.4=Rs.  385.20

Answer 2

Answer:

• Cost of total energy is Rs 112.5 .

Explanation:

Given,

Power of one bulb is 100 watt.

Power of one tube light is 40 watt.

There are are five rooms. So, Total bulb is 5 and tube light is 5.

Power of 5 bulbs = 100 × 5 = 500 watts.

Power of 5 tube lights = 40 × 5 = 200 watts.

Conversion :-

1 kilowatt (kW) = 1000 watt (W)

Bulbs :-

⇒500/1000 kW

⇒0.5 kW

Tube lights :-

⇒200/1000 kW

⇒0.2 kW

Now,

Electrical energy = Power × Time

Electrical energy of 5 bulbs per day :

⇒ Electrical energy = 0.5 × 1

⇒ Electrical energy = 0.5

Electrical energy of 5 bulbs per day is 0.5 kWh

Electrical energy of 5 tube lights per day :

⇒ Electrical energy = 0.2 × 5

⇒ Electrical energy = 1

Electrical energy of 5 tube lights per day is 1 kWh.

Total electrical energy consuming per day = Electrical energy of bulbs + Electrical energy of tube lights

⇒0.5 + 1

⇒1.5 kWh

Total electrical energy consuming in 30 days = 1.5 × 30

⇒45 kWh

1 unit = 1 kWH

1 unit = Rs 2.5

1 kWh = Rs 2.5

So,

For 45 kWh

⇒ 45 × 2.5

⇒ 112.5

Thus,

Cost of total energy is Rs 112.5 .