Jambmaths question:
$\begin{align} & \text{If the variance }3+x,6,4,x,7-x\text{ is 4 and the mean is 5, find the standard deviation} \\ & (A)\text{ }\sqrt{2}\text{ (B) }\sqrt{3}\text{ (C) }2\text{ }(D)\text{ }3 \\\end{align}$
Jamb Maths Solution:
$\begin{align} & \text{Variance}={{\sigma }^{2}}=4 \\ & \text{standard deviation}=\sigma =\sqrt{\text{variance}}=\sqrt{{{\sigma }^{2}}} \\ & \sigma =\sqrt{4}=2 \\ & \text{standard deviation is }2 \\\end{align}$
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