It is given that the output of 60 hp at 2000 rpm is increased by 15% at 2300 rpm.
It is required to find the actual horsepower at 2300 rpm.
To do this, find the value of the 15% increase of 60:
[tex]\frac{100+15}{100}\times60=\frac{115}{100}\times60=69\text{ hp}[/tex]The engine produces 69 hp at 2300 rpm.