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Question: Answered & Verified by Expert
The variance of first 20 natural numbers is
MathematicsStatisticsWBJEEWBJEE 2015
Options:
  • A $133 / 4$
  • B $279 / 12$
  • C 133/2
  • D 399/4
Solution:
2178 Upvotes Verified Answer
The correct answer is: $133 / 4$
Variance of $n$ natural numbers $=\frac{n^{2}-1}{12}=\frac{(20)^{2}-1}{12} \quad$ $[\because n=20]$,
$=\frac{400-1}{12}=\frac{399}{12}=\frac{133}{4}$

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