ECZ 2011 · O-Level Paper 1 — Sets
A set has 6 proper subsets. How many elements does it have?
- A. 3
- B. 2
- C. 6
- D. 4
Verified working — step 1
Here "proper subsets" is being counted as 2^n - 2, excluding both the empty set and the set itself. So 2^n - 2 = 6 gives 2^n = 8 and n = 3. Note the usual definition of a proper subset excludes only the set itself, which would give 2^n - 1 = …The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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