A load of 500 kg was lifted through a distance of 13 cm. by an effort of 25 kg which moved through a distance of 650 cm. The efficiency of the lifting machine is

Answer: Option B

Mechanical advantage (MA) = Load (W)/Effort (P).
MA = W/P = 500/25 = 20.
Velocity ratio (VR) = (Distance moved by the effort (Y))/(Distance moved by the load (X)).
VR = Y/X = 650/13 = 50.
Efficiency = MA/VR = 20/50 = 0.4 i.e. 40%.