SSC JE Mechanical Engineering 2017 Set 2 Paper

For any type of orifice, Coefficient of discharge
$\left({\mathit{C}}_{\mathit{d}}\right)=$ Coeff. of flow/velocity (Cv) × Coeff of contraction (Cc).
where
Cd = actual discharge/theoretical discharge
Cc = Area of vena contract/ area of orifice
Cv = actual velocity at vena contract/theoretical velocity
Coefficient of velocity is varies between 0.98 to 0.99, and coefficient of discharge is varies between 0.67 to 0.69.