Answer: the crate is lifted a distance of 0.245 m.
Explanation: We can use the principle of work to solve this problem, which states that the work done on an object is equal to the force applied times the distance moved in the direction of the force.
First, we need to calculate the work done by the student on the crate:
Work = force x distance
Work = 250 N x 1.6 m
Work = 400 J
Next, we need to calculate the work done on the lever system, taking into account its efficiency:
Efficiency = (work output / work input) x 100%
0.90 = (work output / 400 J) x 100%
Solving for work output:
work output = 0.90 x 400 J
work output = 360 J
Finally, we can use the work output to find the distance the crate is lifted:
Work = force x distance
distance = work / force
distance = 360 J / (150 kg x 9.81 m/s^2)
distance = 0.245 m