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The numbers \(59, 53, 51, 43, 36\), \((8x + 1), (x^2 + 1), 13, 12, 9, 7, 3\) are written in descending order and their median is 25. What is/are the values of x ?

This question was previously asked in
CDS 2 2026 Maths Question Paper (13-Sep-2026)
The correct answer is

4 only

To determine the values of \(x\), given the set of numbers \(59, 53, 51, 43, 36, (8x + 1), (x^2 + 1), 13, 12, 9, 7, 3\) with a median of 25, follow these steps:

  1. First, note that there are 12 numbers in total. As the median is the middle value(s), for 12 numbers, the median will be the average of the 6th and 7th numbers when they are in descending order.
  2. Arrange the non-variable numbers in descending order: \(59, 53, 51, 43, 36, 13, 12, 9, 7, 3\).
  3. Insert the expressions involving \(x\)\(8x + 1\) and \(x^2 + 1\) into the correct positions in the list. We know these fall around the median, so they must be the 6th and 7th, or adjacent.
  4. Given the median is 25, it follows that: \(\frac{(8x + 1) + (x^2 + 1)}{2} = 25\).
  5. Solving this equation: 
\(\begin{align*} \frac{(8x + 1) + (x^2 + 1)}{2} &= 25 \\ 8x + 1 + x^2 + 1 &= 50 \\ x^2 + 8x + 2 &= 50 \\ x^2 + 8x - 48 &= 0 \end{align*}\)
  1. This is a quadratic equation: \(x^2 + 8x - 48 = 0\). Solve it using factorization or the quadratic formula:
  2. Try factorization: 
\(\begin{align*} x^2 + 8x - 48 &= (x - 4)(x + 12) = 0 \\ x &= 4 \quad \text{or} \quad x = -12 \end{align*}\)
  1. Evaluate each solution:
    • If \(x = 4\), then \(8x + 1 = 33\) and \(x^2 + 1 = 17\). Insert these numbers into our sequence: \(59, 53, 51, 43, 36, 33, 17, 13, 12, 9, 7, 3\). The median is indeed 25 (average of 17 and 33).
    • If \(x = -12\), then \(8x + 1 = -95\) and \(x^2 + 1 = 145\). Insert these numbers: \(145, 59, 53, 51, 43, 36, 13, 12, 9, 7, 3, -95\). Here, the median is not 25, so \(x = -12\) is invalid.
  2. Only \(x = 4\) ensures the median is 25, confirming the correct answer is \(4 \text{ only}\).
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Important Questions from Statistics

  1. Match the following:

    (a) Marginalist Revolution(i) Samuelson
    (b) Multiplier-Accelerator model(ii) J. R. Hicks
    (c) IS-LM curves(iii) Jevous
    (d) Real Business Cycle(iv) Robert J. Borro

    Choose the correct option from those given below:

  2. As per the SRS Bulletin of September 2017, the estimated death rate for Kerala is 7.6, while for Bihar it is 6. From these data which is the correct inference to draw?

  3. Arrange the following States in descending order according to Maternal Mortality Ratio (MMR) as per the Special Bulletin of SRS, May, 2018:

    (i) Assam

    (ii) Bihar

    (iii) Madhya Pradesh

    (iv) Uttar Pradesh

    Choose the correct answer from the code given below :

  4. Which of the following statements is true for the Indian economy according to the World Bank figures for 2017?

  5. Harrod's Growth model is given as under:

    \(\begin{array}{ll} \mathrm{S}_{\mathrm{t}}=\alpha \mathrm{Y}_{\mathrm{t}} & 0<\alpha<1 \\ \mathrm{I}_{\mathrm{t}}=\beta\left[\mathrm{Y}_{\mathrm{t}}-\mathrm{Y}_{\mathrm{t}-1}\right] & \beta>0 \\ \mathrm{~S}_{\mathrm{t}}=\mathrm{I}_{\mathrm{t}} & \end{array}\)

    where S t =  Savings, Y t = Income, l t =  Investment, t = time

    In this model for economic growth, the condition for economic growth is

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