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Question: Answered & Verified by Expert
Let $\bar{X}$ and M.D. be the mean and the mean deviation about $\bar{X}$ of $n$ observations $\mathrm{x}_{\mathrm{i}}, \mathrm{i}=1,2$,n. If each of the observations is increased by 5 , then the new mean and the mean deviation about the new mean, respectively, are :
MathematicsStatisticsJEE MainJEE Main 2014 (12 Apr Online)
Options:
  • A
    $\bar{X}$, M.D.
  • B
    $\overline{\mathrm{X}}+5$, M.D.
  • C
    $\bar{X}$, M.D. $+5$
  • D
    $\overline{\mathrm{X}}+5$, M.D. $+5$
Solution:
1979 Upvotes Verified Answer
The correct answer is:
$\overline{\mathrm{X}}+5$, M.D.
Let $x_i$ be $n$ observations, $i=1,2, \ldots n$ Let $\bar{X}$ be the mean and M.D be the mean deviation about $\bar{X}$. If each observation is increased by 5 then new mean will be $\bar{X}+5$ and new M.D. about new mean will be M.D.
$$
\left(\because \text { Mean }=\sum_{i=1}^n \frac{x_i}{n}\right)
$$

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