NIMCET 2021
There are 50 questions in a paper. The number of ways in which a student can attempt one or more questions is
Answer (Detailed Solution Below)View answer ▾Hide ▴
Answer: Option A —
Detailed Solution
Each question is either attempted or skipped: choices in all.
Remove the one way in which nothing is attempted: .
✓ Check
With 2 questions the ways are {1}, {2}, {1, 2}: .⚠ Common trap
(C) also removes 'attempt all', which is allowed.Quick tip
Each question: attempt or skip, ways; remove the all-skip case
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Permutations & Combinations — Preparation
This question tests your understanding of Permutations & Combinations, a key topic in the Quantitative Aptitude section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
Permutations count arrangements where order matters, while combinations count selections where order does not matter. This topic covers the fundamental principle of counting, factorials, nPr and nCr, arrangements of letters in a word (including repeated letters), circular arrangements, and selecting committees or teams with conditions. The hardest part is deciding whether a question needs a permutation or a combination. Ask yourself whether swapping two chosen items gives a new outcome. If it does, order matters. Conditions such as "two people must sit together" are handled by treating them as a single unit, and "at least one" questions are usually easiest to solve as total minus none. Practise the permutation and combination questions below, each with a step-by-step solution showing how to set up the count.