Five 80-W and three 100W are run for 8 hours. If the cost of energy

PHYSICS
WAEC 2007

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]

  • A. N280.00
  • B. N28.00
  • C. N7.20
  • D. N1.44

Correct Answer: B. N28.00

Explanation

P = (80 x 5 + 100 x 3)8

= 5600W

Cost = \(\frac{5600}{1000} \times 5 = N28\)



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