Question 45

waecmaths question: 

Find the mean deviation of 20, 30, 25, 40 35, 50, 45, 40, 20 and 45

Option A: 

8

Option B: 

9

Option C: 

10

Option D: 

12

waecmaths solution: 

$\begin{align}  & Mean=\bar{x}=\frac{20+30+25+40+35+50+45+40+20+45}{10} \\ & Mean=\bar{x}=\frac{350}{10}=35 \\ & \text{Mean deviation}=\frac{\left| 20-35 \right|+\left| 30-35 \right|+\left| 25-35 \right|+\left| 35-35 \right|+\left| 50-35 \right|+\left| 45-35 \right|+\left| 40-35 \right|+\left| 20-35 \right|+\left| 45-35 \right|}{10} \\ & \text{Mean deviation}=\frac{85}{10}=8.5 \\\end{align}$

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