A house is installed with 
(a) 10 bulbs of 60 W each of which is used 5 hours daily. 
(b) 4 fans of 75 W each of which runs 10 hours daily. 
(c) One T.V. of 100 W which is used for 5 hours daily. 
(d) One electric iron of 1000 W which is used for 2 hours daily. If the cost of one unit of electricity is Rs.4. 
Find the monthly expenditure of electricity (one month=30 days). Ans. (Rs. 1020/-)


Data Given:

(a)
Power of 10 Bulbs of 60 W each  = 10 ｘ 60 W = 600 W
Time of 10 Bulb each used daily = 5 hrs 
Time for 3o days = 30 ï½˜ 50 hrs = 150 hrs

(b)
Power of 4 Fans of 75 W each  = 10 ｘ 75 W = 750 W
Time of  4 Fans used daily  =  4 hrs 
Time for 3o days = 30 ï½˜ 4 hrs = 120 hrs

(c)
Power of 1 T.V.   = 100 W
Time of  1 T.V. used daily for 2hrs = 5 hrs
Time for 3o days = 30 ï½˜ 5 hrs = 150 hrs

(d)
Power of 1 Iron   = 1000 W
Time of  1 Iron used daily for 2hrs = 2 hrs
Time for 3o days = 30 ï½˜ 2 hrs = 60 hrs

Cost of one unit of Electricity = Rs. 4 per Unit


To Find:


Monthly (30 days) expenditure (cost) of Electricity = ?



Solution:


Formula for Energy consumed in KWh [(Power (in Watt), Time (in Hours) and 1KWh = 1 unit]

E= `\frac{Power ｘ Time}{1000}`

(a)
Monthly Energy consumed by 10 Bulb in units:

E(bulb) = `\frac{Power ｘ Time}{1000}`

By putting values

E(bulb) = `\frac{600 Wattsｘ 150 hrs}{1000}`

E(bulb) = 90 KWh 

E(bulb) = 90 units



(b)
Monthly Energy consumed by 4 fans monthly in units:

E(fans) = `\frac{Power ｘ Time}{1000}`

By putting values

E(fans) = `\frac{300 Wattsｘ 300 hrs}{1000}`

E(fans) = 90 KWh 

E(fans) = 90 units



(c)
Monthly Energy consumed by 1 T.V. in units:

E(T.V.) = `\frac{Power ｘ Time}{1000}`

By putting values

E(T.V.) = `\frac{100 Wattsｘ 150 hrs}{1000}`

E(T.V.) = 15 KWh 

E(T.V.) = 15 units



(d)
Energy consumed by Iron:

E(Iron) = `\frac{Power ｘ Time}{1000}`

By putting values

E(Iron) = `\frac{1000 Wattsｘ 60 hrs}{1000}`

E(Iron) = 60 KWh 

E(Iron) = 60 units




Total Energy consumed in a month in Units

E (Total) = E(bulb) + E(fans) + E(T.V.) + E(Iron) 

E (Total)  = (90 + 90 + 15 + 60) units 

E (Total)  = 255 units

Cost of one unit of Electricity = Rs. 4 per Unit
so,
Monthly expenditure (cost) of electricity = 255 units ｘ Rs. 4 per Unit 

Monthly expenditure (cost) of electricity = 1020 Rs.

So, the monthly expenditure of using the questioned home appliances according to the given data is Rs. 1020. 

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