A tiered electricity bill — Caselets Aptitude Question
A tiered electricity bill: Electricity costs ₹5 per unit for the first 100 units and ₹8 per unit thereafter. Answer and worked solution on CodeKairo.
- Topic: Caselets
- Section: Data Interpretation
- Difficulty: Medium
- Time target: 75 seconds
Question
Electricity costs ₹5 per unit for the first 100 units and ₹8 per unit thereafter. A household uses 250 units.
What is the bill?
Options
- ₹1,500
- ₹1,700
- ₹1,900
- ₹2,000
Show the answer and the worked solution
Correct answer: B. ₹1,700
Worked solution
- First 100 units: 100 × 5 = ₹500.
- Next 150 units: 150 × 8 = ₹1,200.
- Total = ₹1,700.
Answer: ₹1,700.
The idea
Tiered pricing charges each band at its own rate. Applying the higher rate to everything gives ₹2,000, the offered trap.
Shortcut. Charge everything at ₹8, then refund the cheap band: 250 × 8 = 2,000, minus 100 × 3 = 300, gives ₹1,700.
Common trap. "₹2,000" — charging all 250 units at ₹8 and ignoring the cheaper first 100.