In a house, 3 bulbs of 25 W each are used for five hours a day. Calculate the units of electricity consumed in 31 days. Also, find total expenditure if one unit costs rupees 2.50.

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A house hold use one heater of rated power 1000w for 1 hour a day, five bulbs of power 40w used for 5 hours a day and the fan of rated power 100w used for 10 hours a day. Find the number of units of electirical energy consumed in 10 days.

Electric energy consumed=Power×time Heater, =1000×1=1000 Wh Bulb,=5×40×5=1000 Wh Fan, =100×10=1000 Wh Total=3000 Wh for one day. For 10 days=3000×10=30000 Wh 1 unit = 1 kW h = 1000 Wh 1 W h = (1/1000) unit 30000 W h = 30 unit Electrical energy consumed in 10 days = 30 unit

Electric energy consumed=Power×time

Heater, =1000×1=1000 Wh
Bulb,=5×40×5=1000 Wh
Fan, =100×10=1000 Wh
Total=3000 Wh for one day.

For 10 days=3000×10=30000 Wh

1 unit = 1 kW h = 1000 Wh
1 W h = (1/1000) unit
30000 W h = 30 unit
Electrical energy consumed in 10 days = 30 unit