Question

Energy out and Energy in of a system are 10 J and 20 J respectively, what is the efficiency of the system?

(a) 20%

(b) 30%

(c) 40%

(d) 50%

The question was asked during an interview.

This interesting question is from Efficiency in chapter Energy Balances that Include the Effects of Chemical Reaction, Ideal Processes, Efficiency and the Mechanical Energy Balance and Heats of Solution and Mixing of Basic Chemical Engineering

Answer 1

The correct answer is (d) 50%

For explanation I would say: Efficiency = 10/20*100 = 50%.