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JAMB Physics 2013 Paper

Question : 33

Total: 43

Solution:

Concept:

Electricity cost depends on the total energy consumed in kilowatt-hours multiplied by the cost per unit.

Explanation:

Calculate the total power of all bulbs:

P = (10 \times 40) + (5 \times 100)

P = 400 + 500 = 900\text{ W}

Convert watts to kilowatts:

900\text{ W} = 0.9\text{ kW}

Energy used in 10 hours:

E = 0.9 \times 10 = 9\text{ kWh}

Since 1 unit is 1 kWh, the cost is:

\text{Cost} = 9 \times 5 = 45

Thus, the total cost is N45.

Answer:

The correct answer is N45, option C.

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