NECO 2001 Physics · Question 10

If N.E.P.A. charges 65 kobo per kilowatt-hour for electricity supplied to consumers, what bill would an…

Question

If N.E.P.A. charges 65 kobo per kilowatt-hour for electricity supplied to consumers, what bill would an electric iron rated at 750 watts attract when used for 24 hours?

A.N9.70
B.N11.70
C.N12.40
D.N15.90
E.N17.60

Answer: B. N11.70

Explanation written with AI and checked against the answer key

Analyze the question: We need the cost of running a 750 W iron for 24 hours at 65 kobo per kWh.

Concept: Electrical energy (kWh) = Power (kW) × Time (hours) Cost = Energy (kWh) × Rate per kWh

Solution:

Convert power to kilowatts: 750 W = 750 ÷ 1000 = 0.75 kW

Calculate the energy used: Energy = 0.75 kW × 24 h = 18 kWh

Calculate the cost: Cost = 18 × 65 kobo = 1170 kobo

Convert to naira (100 kobo = N1): 1170 ÷ 100 = N11.70

Tip: In "bill" questions, follow this order: W → kW → kWh → cost → naira. Always convert kobo to naira at the end by dividing by 100. A shortcut: 18 × 0.65 = 11.70.

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