If an elevator uses 1200 N of force to carry 1000 N of people up 6 m how efficient is it?

The efficiency of the elevator can be calculated using the work input and work output. In this case, the work input is force x distance = 1200 N x 6 m = 7200 Nm, and the work output is force x distance = 1000 N x 6 m = 6000 Nm. Efficiency is work output / work input x 100%, so (6000 Nm / 7200 Nm) x 100% ≈ 83.3% efficient.