Answer:
0.784
Explanation:
Efficiency is the ratio of energy out over energy in.
We know the energy in was 1250 J.
The energy out is the change in potential energy of the box:
PE = mgh
PE = (25 kg) (9.8 m/s²) (4 m)
PE = 980 J
So the efficiency is:
e = 980 J / 1250 J
e = 0.784