Let the median and the mean deviation about the median of 7 observation $170,125,230,190,210$, a, b be 170 and $\frac{205}{7}$ respectively. Then the mean deviation about the mean of these 7 observations is :
Solution
$\text { Median }=170 \Rightarrow 125, \mathrm{a}, \mathrm{b}, 170,190,210,230$
<br/><br/>Mean deviation about
Median $=$
<br/><br/>$$
\begin{aligned}
& \frac{0+45+60+20+40+170-a+170-b}{7}=\frac{205}{7} \\\\
& \Rightarrow \mathrm{a}+\mathrm{b}=300 \\\\
& \text { Mean }=\frac{170+125+230+190+210+a+b}{7}=175
\end{aligned}
$$
<br/><br/>Mean deviation
About mean $=$
<br/><br/>$\frac{50+175-a+175-b+5+15+35+55}{7}=30$
About this question
Subject: Mathematics · Chapter: Statistics · Topic: Measures of Central Tendency
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