EPFO 2015 English Medium Solved Paper

Given, sequence = 27, 28. 29...... . 93
This is an arithmetic progression.
Here, a = 27, d = 28 - 27 = 1
So, ${\mathit{T}}_{\mathit{n}}=\mathit{a}+(\mathit{n}-1)\mathit{d}$
⇒ 93 = 27 + (n -1 ) 1
⇒n - 1 = 66
∴ $\mathit{n}=67$
Sum, ${\mathit{S}}_{\mathit{n}}=\frac{\mathit{n}}{2}$[$$ $2\mathit{a}+\left(\mathit{n}-1\right)\mathit{d}$ ]
$=\frac{67}{2}\left[2\times 27+\left(67-1\right)1\right]$
$=\frac{67}{2}$[54+66]= $\frac{67\times 120}{2}$
$=4020$
Hence, required arithmetic average
= $\frac{\mathrm{Sum}\mathrm{}\mathit{o}\mathit{f}\mathrm{numbers}}{\mathrm{Total}\mathrm{numbers}}$ $=\frac{4020}{67}=60$