Average daily energy use: Over a 14-day period your meter shows 18 kWh consumed. What is the average daily energy usage expressed in kWh per day?

Difficulty: Easy

Correct Answer: 1.286 kWh

Explanation:

Introduction / Context:Electric utility data are typically given in kilowatt-hours over billing periods. Estimating average daily usage helps compare different periods and identify energy-saving opportunities. Here we compute the daily average from a total over two weeks.

Given Data / Assumptions:

  • Total energy E_total = 18 kWh.
  • Time window = 14 days.
  • Assume uniform average use over the period for calculation purposes.

Concept / Approach:

Average daily energy = total energy / number of days. Because the question requests kWh per day, no time conversion is needed beyond dividing by days.

Step-by-Step Solution:

Compute average: E_avg_per_day = 18 kWh / 14 days.Perform division: 18 / 14 ≈ 1.2857.Round suitably: ≈ 1.286 kWh per day.Therefore, the average daily energy use is about 1.286 kWh.

Verification / Alternative check:

Cross-check: At 1.286 kWh/day for 14 days, total ≈ 18.0 kWh, matching the meter reading.

Why Other Options Are Wrong:

12.85 kWh/day would imply 179.9 kWh over 14 days, not 18 kWh. 535 kWh and 252 kWh are grossly inconsistent. 0.1286 kWh/day is 10× too small.

Common Pitfalls:

Confusing kW (power) with kWh (energy). Forgetting to divide by the exact number of days in the period.

Final Answer:

1.286 kWh

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