WAEC - Physics (2007 - No. 40)
Five 80-W and three 100W are run for 8 hours. If the cost of energy is N5.00 per unit, calculate the cost of running the lamp. [1 unit = 1 kWh]
N280.00
N28.00
N7.20
N1.44
Explanation
P = (80 x 5 + 100 x 3)8
= 5600W
Cost = \(\frac{5600}{1000} \times 5 = N28\)
= 5600W
Cost = \(\frac{5600}{1000} \times 5 = N28\)
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