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Day 362: NDA Maths

5 questions (6 parts). Try each one first, then open its answer.

  1. Question 1

    Lines. Asked once: NDA 1 2019

    57
    If the lines 3y+4x=13y+4x=1, y=x+5y=x+5 and 5y+bx=35y+bx=3 are concurrent, then what is the value of b?

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  2. Question 2 (case study, 2 parts)

    Matrices & Determinants. Asked once: NDA 1 2023

    Consider the following for the next two (02) items that follow: Let Δ(a,b,c,α)=∣abaα+bbcbα+caα+bbα+c0∣\Delta(a,b,c,\alpha)=\begin{vmatrix}a&b&a\alpha+b\\b&c&b\alpha+c\\a\alpha+b&b\alpha+c&0\end{vmatrix}.
    51
    If Δ(a,b,c,α)=0\Delta(a,b,c,\alpha)=0 for every α>0\alpha>0, then which one of the following is correct?

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    52
    If Δ(7,4,2,α)=0\Delta(7,4,2,\alpha)=0, then α\alpha is a root of which one of the following equations?

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  3. Question 3

    Probability. Asked once: NDA 2 2022

    111
    A box contains 2 white balls, 3 black balls and 4 red balls. What is the number of ways of drawing 3 balls from the box with at least one black ball?

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  4. Question 4

    Sequence & Series. Asked once: NDA 1 2017

    17
    The sum of the roots of the equation ax2+x+c=0ax^2 + x + c = 0 (where aa and cc are non-zero) is equal to the sum of the reciprocals of their squares. Then a, ca2, c2a,\, ca^2,\, c^2 are in

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  5. Question 5

    Statistics. Asked once: NDA 2 2018

    120
    In which one of the following cases would you expect to get a negative correlation?

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