Mathematics · Probability

JEE Main 2026 — 23 January, Morning Shift — Question 13

Let the mean and variance of 8 numbers −10,−7,−1,x,y,9,2,16-10,-7,-1, x, y, 9,2,16 be 72\frac{7}{2} and 2934\frac{293}{4}, respectively. Then the mean of 4 numbers x,y,x+y+1,∣x−y∣\mathrm{x}, \mathrm{y}, \mathrm{x}+\mathrm{y}+1,|\mathrm{x}-\mathrm{y}| is:

  1. Option A:

    11

    Correct
  2. Option B:

    9

  3. Option C:

    10

  4. Option D:

    12

Answer: A

Step-by-step solution

Mean =−18+x+y+2+9+168=73=\frac{-18+\mathrm{x}+\mathrm{y}+2+9+16}{8}=\frac{7}{3}

=x+y+98=72⇒x+y+9=28\begin{gathered} =\frac{x+y+9}{8}=\frac{7}{2} \Rightarrow x+y+9=28 \end{gathered} Variance =∑zi28−(μ)2=2934=\frac{\sum \mathrm{z}_{\mathrm{i}}^{2}}{8}-(\mu)^{2}=\frac{293}{4} ⇒102+72+12+x2+y2+22+92+1628−(72)2=2934\begin{gathered} \Rightarrow \frac{10^{2}+7^{2}+1^{2}+\mathrm{x}^{2}+\mathrm{y}^{2}+2^{2}+9^{2}+16^{2}}{8}-\left(\frac{7}{2}\right)^{2}=\frac{293}{4} \end{gathered} Solving & ⇒x=12,y=7\Rightarrow \mathrm{x}=12, \mathrm{y}=7

Mean of (1+x+y),x,y,∣y−x∣(1+x+y), x, y,|y-x| is ⇒20+12+7+54=444=11\Rightarrow \frac{20+12+7+5}{4}=\frac{44}{4}=11

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Probability
Topic
Mean, variance, expected values of distributions