Answer
a) 26.8%
b) 7.05%
c) 77.0%
Work Step by Step
We know that the maximum efficiency is given by:
$$e_{max}=1- \frac{T_c}{T_h}$$
Where $T_c$ is the cold temperature, $T_h$ is the hot temperature, and $e_{max} $ is the maximum efficiency.
Now, plug in the given values, remembering to convert to Kelvin. This means that the efficiencies are:
a) 26.8%
b) 7.05%
c) 77.0%
