Answer:
The temperature of the low temperature thermal reservoir is 300 K.
Explanation:
All reversible power cycles are equivalent to the Carnot's cycle, whose equation for efficiency is:
[tex]\eta_{th} =1-\frac{T_{L}}{T_{H}}[/tex] (Eq. 1)
Where:
[tex]\eta_{th}[/tex] - Thermal efficiency, dimensionless.
[tex]T_{H}[/tex] - High temperature reservoir, measured in Kelvin.
[tex]T_{L}[/tex] - Low temperature reservoir, measured in Kelvin.
Now we proceed to clear the low temperature reservoir within:
[tex]\frac{T_{L}}{T_{H}} = 1-\eta_{th}[/tex]
[tex]T_{L} = (1-\eta_{th})\cdot T_{H}[/tex]
If [tex]\eta_{th} = 0.75[/tex] and [tex]T_{H} = 1200\,K[/tex], then:
[tex]T_{L} = (1-0.75)\cdot (1200\,K)[/tex]
[tex]T_{L} = 300\,K[/tex]
The temperature of the low temperature thermal reservoir is 300 K.
