SSC CHSL 19 Apr 2021 Shift 3 Paper

Given, average of 5 numbers $=26.4$
$\therefore$ Sum of 5 numbers
$=$ Average $\times$ Total numbers
$=26.4\times 5=132$
Given, first number $=\frac{1}{5}\times$
(Sum of four numbers)
$\Rightarrow$ First number $=\frac{1}{5}\times$
[Sum of 5 numbers - First number]
$\Rightarrow$ First number $+\frac{1}{5}$ First number
$=\frac{1}{5}\times 132$
$\therefore$ First number $=\frac{1}{5}\times 132\times \frac{5}{6}=22$