Efficiency = 61.54%
Efficiency is given by the Formula;
Efficiency = work output/work input × 100%
Work input = Input force × distance moved by the input force
= 13 N × 0,25
= 3.25 Joules
Work output or work done by the screwdriver is 2 Joules
Therefore;
Efficiency = 2/3.25 ×100%
= 61.54%