Case study·Hard exam skill (4/5)·No calculatorNeeds mentor review
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
The observations are each increased by
Total: 4 marks
(a) Find the mean of the original readings. (1 mark)
(b) Find the variance of the original readings. (2 marks)
(c) State the variance of the recalibrated readings and justify it. (1 mark)
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