Answer:
496.7 K
Explanation:
The efficiency of a Carnot engine is given by the equation:
[tex]\eta = 1 - \frac{T_H}{T_L}[/tex]
where:
[tex]T_H[/tex] is the temperature of the hot reservoir
[tex]T_C[/tex] is the temperature of the cold reservoir
For the engine in the problem, we know that
[tex]\eta = 0.400[/tex] is the efficiency
[tex]T_C = 298.0 K[/tex] is the temperature of the cold reservoir
Solving for [tex]T_H[/tex], we find:
[tex]\frac{T_C}{T_H}=1-\eta\\T_H = \frac{T_C}{1-\eta} =\frac{298.0}{1-0.400}=496.7 K[/tex]