PYQ Vault

Day 14: NDA Maths

5 questions (7 parts). Try each one first, then open its answer.

  1. Question 1 (case study, 2 parts)

    Limits & Continuity. This type asked 4 times: NDA 2 2021, NDA 2 2023, NDA 1 2024, NDA 1 2025. This one: NDA 1 2025

    Let the function f(x)=sin⁡[x]f(x) = \sin[x], where [⋅][\cdot] is the greatest integer function and g(x)=∣x∣g(x) = |x|.
    83
    What is lim⁡x→0{f(x)⋅g(x)}\lim_{x\to 0}\{f(x) \cdot g(x)\} equal to?

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    84
    What is lim⁡x→0f(x)g(x)\lim_{x\to 0} \frac{f(x)}{g(x)} equal to?

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  2. Question 2

    Matrices & Determinants. This type asked 4 times: NDA 2 2017, NDA 2 2019, NDA 2 2023, NDA 1 2025. This one: NDA 1 2025

    27
    If A=(122212221)A = \begin{pmatrix} 1 & 2 & 2 \\ 2 & 1 & 2 \\ 2 & 2 & 1 \end{pmatrix} then what is A2−4AA^2 - 4A equal to? (where I3I_3 is the identity matrix of order 3)

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  3. Question 3

    Permutation & Combination. This type asked 4 times: NDA 1 2019, NDA 1 2020, NDA 1 2022, NDA 1 2025. This one: NDA 1 2025

    28
    If the number of selections of rr as well as (n+r)(n+r) things from 5n5n different things are equal, then what is the value of rr?

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  4. Question 4

    Permutation & Combination. This type asked 4 times: NDA 1 2020, NDA 1 2022, NDA 2 2024, NDA 1 2025. This one: NDA 1 2025

    18
    In how many ways can the letters of the word DELHI be arranged keeping the positions of vowels and consonants unchanged?

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  5. Question 5 (case study, 2 parts)

    Probability. This type asked 4 times: NDA 1 2017, NDA 2 2017, NDA 1 2020, NDA 1 2025. This one: NDA 1 2025

    A committee of 6 members is formed from a group of 7 gentlemen and 4 ladies.
    109
    What is the probability that the committee includes exactly 3 gentlemen?

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    110
    What is the probability that the committee includes at least 2 ladies?

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