If the variance σ ^ 2 of the data cases x _ i & 0 & 1 & 5 & 6 & 10...

Finding the ${f}_{i}{x}_{i} \text{ and } {f}_{i}{{x}_{i}}^{2}$ we get, 

Now, from above table we get, $∑ {f}_{i}{x}_{i} = 176$

Now, finding $\overset{¯}{x} = \dfrac{∑ {f}_{i}{x}_{i}}{∑ {f}_{i}} = \dfrac{176}{22} = 8$

Now, finding variance, we get,

${\sigma}^{2} = \dfrac{1}{N} ∑ {f}_{i}{x}_{i} - 2 ( \overset{¯}{x}{)}^{2}$

$⇒ {\sigma}^{2} = \dfrac{1}{22} \times 2048 - ( 8{)}^{2}$

$⇒ {\sigma}^{2} = 93 . 090964$

$⇒ {\sigma}^{2} = 29 . 0909$

$⇒ \left[{\sigma}^{2}\right] = \left[29 . 0909\right] = 29$