Hard MCQ +4 / -1 PYQ · JEE Mains 2020

For the frequency distribution :
Variate (x) :      x1   x2   x3 ....  x15
Frequency (f) : f1    f2   f3 ...... f15
where 0 < x1 < x2 < x3 < ... < x15 = 10 and
$\sum\limits_{i = 1}^{15} {{f_i}}$ > 0, the standard deviation cannot be :

  1. A 6 Correct answer
  2. B 1
  3. C 4
  4. D 2

Solution

If variate varries from m to M then variance <br><br>${\sigma ^2} \le {1 \over 4}{\left( {M - m} \right)^2}$ <br><br>(M = upper bound of value of any random variable, <br><br> m = Lower bound of value of any random variable) <br><br>Here M = 10 and m = 0 <br><br>$\therefore$ ${\sigma ^2} \le {1 \over 4}{\left( {10 - 0} \right)^2}$ <br><br>$\Rightarrow$ ${\sigma ^2} \le 25$ <br><br>$\Rightarrow$ $- 5 \le \sigma \le 5$ <br><br>$\therefore$ $\sigma$ $\ne$ 6

About this question

Subject: Mathematics · Chapter: Statistics · Topic: Measures of Central Tendency

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