Case study·Hard exam skill (4/5)·No calculator
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Question
A room uses two W lamps for h, one W fan for h and a kW heater for h in a day. Electricity costs Rs per kWh.
Total: 4 marks
(a) Find the energy used by the two lamps. (1 mark)
(b) Find the total energy used in the day. (2 marks)
(c) Find the cost for the day. (1 mark)
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