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TS EAMCET · Maths · Statistics

If \(S_1\) and \(S_2\) are the variances of the first \(2 k\) and \(k(k>1)\) natural numbers respectively, then \(\left(S_1 / S_2\right)\) lies in the interval

  1. A \([4, \infty)\)
  2. B \((1,4]\)
  3. C \((4,5]\)
  4. D \([7, \infty)\)
Verified Solution

Answer & Solution

Correct Answer

(B) \((1,4]\)

Step-by-step Solution

Detailed explanation

The variance of first \(2 k\) natural numbers \(S_1=\frac{2 k(2 k+1)(4 k+1)}{6 \times 2 k}-\left(\frac{2 k(2 k+1)}{2 \times 2 k}\right)^2\) \(=(2 k+1)\left[\frac{4 k+1}{6}-\frac{2 k+1}{4}\right]\) \(=\frac{2 k+1}{12}[8 k+2-6 k-3]=\frac{4 k^2-1}{12}\) and variance of first \(k\)…