ECAT Mathematics — Sequences and Series
Sequences and Series is part of the Mathematics section of the UET ECAT (30 of the 100 MCQs). It breaks into 5 subtopics, and we hold 38 ECAT-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (5)
How Sequences and Series is tested
Across the 7 ECAT past papers on ParhaiKrlo, Sequences and Series accounts for 10 questions. It appears in 4 of them, about 2.5 questions a paper. The heaviest was ECAT Past Paper 02, with 5 questions, and the most recent is ECAT Past Paper 07, with 1.
| Paper | Questions |
|---|---|
| ECAT Past Paper 07 | 1 |
| ECAT Past Paper 04 | 2 |
| ECAT Past Paper 02 | 5 |
| ECAT Past Paper 01 | 2 |
Sequences and Series MCQs from the ECAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · ECAT Past Paper 07 · Sequences and Series
The kth term of a series is 2ᵏ3⁻ᵏ. The sum of the first 100 terms is approximately:
- A.2
- B.1.5
- C.1
- D.(2/3)¹⁰⁰
Show answer
Answer: A. 2 — Terms are (2/3)ᵏ, a GP with a = r = 2/3; the sum of 100 terms ≈ S∞ = (2/3)/(1/3) = 2.
- Q2 · ECAT Past Paper 04 · Sequences and Series
An arithmetic progression has a first term of 12 and a fifth term of 18. The sum of the first 25 terms is:
- A.400
- B.350
- C.750
- D.150
Show answer
Answer: C. 750 — d = (18 − 12)/4 = 1.5; S₂₅ = 25/2 × (24 + 24 × 1.5) = 12.5 × 60 = 750.
- Q3 · ECAT Past Paper 02 · Sequences and Series
If the first term of an A.P. is 6 and its 5th term is 14, then its 20th term is:
- A.44
- B.46
- C.43
- D.14
Show answer
Answer: A. 44 — 6 + 4d = 14 gives d = 2; T₂₀ = 6 + 19 × 2 = 44.