ECAT Mathematics — Permutations, Combinations and Probability
Permutations, Combinations and Probability is part of the Mathematics section of the UET ECAT (30 of the 100 MCQs). It breaks into 3 subtopics, and we hold 34 ECAT-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (3)
How Permutations, Combinations and Probability is tested
Across the 7 ECAT past papers on ParhaiKrlo, Permutations, Combinations and Probability accounts for 5 questions. It appears in 4 of them, about 1.3 questions a paper. The heaviest was ECAT Past Paper 01, with 2 questions, and the most recent is ECAT Past Paper 07, with 1.
| Paper | Questions |
|---|---|
| ECAT Past Paper 07 | 1 |
| ECAT Past Paper 04 | 1 |
| ECAT Past Paper 03 | 1 |
| ECAT Past Paper 01 | 2 |
Permutations, Combinations and Probability MCQs from the ECAT past papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · ECAT Past Paper 07 · Permutations, Combinations and Probability
A box contains 15 red, 10 green and 5 yellow toffees. Asim picks 2 green toffees and 1 red toffee and eats them. What is the probability that Irfan will now pick a green toffee?
- A.10/30
- B.8/27
- C.8/30
- D.8/22
Show answer
Answer: B. 8/27 — 27 toffees remain, of which 8 are green.
- Q2 · ECAT Past Paper 04 · Permutations, Combinations and Probability
ⁿC₂ is equal to:
- A.n(n + 1)/2
- B.n!/2
- C.n(n − 1)
- D.n(n − 1)/2
Show answer
Answer: D. n(n − 1)/2 — ⁿC₂ = n!/[2!(n − 2)!] = n(n − 1)/2.
- Q3 · ECAT Past Paper 03 · Permutations, Combinations and Probability
A die is thrown. What is the probability of getting an odd number?
- A.1
- B.1/2
- C.1/6
- D.2/√3
Show answer
Answer: B. 1/2 — Odd outcomes {1, 3, 5}: 3 of 6 = 1/2.