SSC JE Mechanical Engineering 2018 Set 5 Paper

${\mathit{C}}_{\mathit{s}}=\frac{\mathrm{Maximum}\mathrm{fluctuation}}{\mathrm{mean}\mathrm{speed}}$
The ratio of the max fluctuation of speed to the mean speed is called coefficient of fluctuation of speed.
${\mathit{C}}_{\mathit{s}}=\frac{\left({\mathit{N}}_1-{\mathit{N}}_2\right)}{\mathit{N}}$
$=\frac{2\left({\mathit{N}}_1-{\mathit{N}}_2\right)}{{\mathit{N}}_1+{\mathit{N}}_2}$
where${\mathit{N}}_1$ = max speed in r.p.m.
${\mathit{N}}_2$ = min speed in r.p.m.
N = mean speed in r.p.m.
$=\frac{\left({\mathit{N}}_1+{\mathit{N}}_2\right)}{2}$