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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