Answer
31.66%
Explanation:
Output of the stem engine=9.5 KW
Steam engine receives heat at the rate of 1800 KJ/min so [tex]Q_in=1800KJ/min[/tex] we know that 1 minute = 60 sec so [tex]Q_in=1800KJ/min=\frac{1800}{60}=30KJ/sec[/tex]
Now efficiency [tex]\eta =\frac{output}{Q_{in}}=\frac{9.5}{30}=0.3166[/tex]
So efficiency = 0.3166×100=31.66%