Answer:
4 times
Explanation:
Given:
diameter of the input piston, 
diameter of the output piston, 
In such mechanical arrangements the fluid acts as an incompressible link and the pressure remains uniform throughout the fluid bulk.
Then, by the Pascal's law:

where:
are the input and the output forces respectively.
are the input and the output area of pistons respectively.




Efficiency = (Wanted) energy out ÷ energy in × 100
Energy in = 400J
Wanted Energy out = 240J
Energy cannot be used up, only transferred, so the remaining energy is most likely to be transferred into unwanted energy (loss of energy) such as heat energy.
Efficiency = 240 ÷ 400 × 100
Efficiency = 0.6 × 100
Efficiency = 60%