flywheels and turning moment diagrams

A single cylinder, single acting, four stroke gas engine develops 20 kW at

300 r.p.m. The work done by the gases during the expansion stroke is three times the work done on

the gases during the compression stroke, the work done during the suction and exhaust strokes

being negligible. If the total fluctuation of speed is not to exceed ± 2 per cent of the mean speed and

the turning moment diagram during compression and expansion is assumed to be triangular in

shape, find the moment of inertia of the flywheel.