Question

The list of home appliances and their corresponding wattages (for single equipment) and usage is given below. Calculate the amount to be paid as the electricity bill for one month (30 days). The cost of one unit of electricity is Rs. 3.08. Home Appliance Wattage (W) No. of hours used per day Computer Mixer Grinder Ceiling Fan Air conditioner 4 CFL Bulbs

100	10.5
450	2.15
60	9.5
1600	0.75
15	16

• A. Rs. 209.75
• B. Rs. 438.67
• C. Rs. 877.34
• D. Rs. 292.45

Answer 1

The correct option is B Rs. 438.67

Energy consumed in a day by:
(a) Computer
$E_1=100\times 10.5$
$E_1=1050Wh=1.05kWh$
(b) Mixer Grinder
$E_2=450\times 2.15$
$E_2=967.5Wh=0.9675kWh$
(c) Ceiling Fan
$E_3=60\times 9.5$
$E_3=570Wh=0.57kWh$
(d) Air conditioner
$E_4=1600\times 0.75$
$E_4=1200Wh=1.2kWh$
(e) 4 CFL bulbs
$E_5=4\times 15\times 16$
$E_5=960Wh=0.96kWh$

Total energy consumed in a day:
$E=E_1+E_2+E_3+E_4+E_5$
$E=1.05+0.9675+0.57+1.2+0.96$
$E=4.7475kWh$

Total energy consumed in a month:
$E^{\prime }=30\times 4.7475=142.425kWh$
$E^{\prime }=142.425\text{units}$

Cost per unit, $C_u=\text{Rs.}3.08$
Hence, the amount to be paid for the month
$C=E^{\prime }{C}_u==142.425\times 3.08$
$C=\text{Rs.}438.669$