Question 23

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Jambmaths question: 

Find the variance 2x, 2x – 1 and 2x + 1

Option A: 

$\frac{\sqrt{2}}{3}$

Option B: 

2

Option C: 

1

Option D: 

$\frac{2}{3}$

Jamb Maths Solution: 

$\begin{align}  & mean=\overline{x}=\frac{2x+2x-1+2x+1}{3}=\frac{6x}{3}=2x \\ & variance=\frac{{{\left| 2x-2x \right|}^{2}}+{{\left| 2x-1-2x \right|}^{2}}+{{\left| 2x+1-2x \right|}^{2}}}{3} \\ & variance=\frac{0+1+1}{3} \\ & variance=\frac{2}{3} \\\end{align}$

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