ECZ 2016 · O-Level Paper 1 — Sequences and Series
For the same progression (first term 100, common difference −5), find the sum of the first ten terms.
- A. 700
- B. 550
- C. 775
- D. 1000
Verified working — step 1
S₁₀ = n⁄2[2a + (n − 1)d] = 10⁄2[2(100) + 9(−5)] = 5[200 − 45] = …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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