3. A steam engine does 2500 J of useful work to move a wheel through half a rotation. The energy provided to the steam engine by heat for this work equals 7576 J. Calculate the efficiency of the engine.

Repeated trials allow you to calculate a mean which can reduce the effect of random errors to make your results more precise.your results will also be reproducible therefore if someone else did the same experiment they'd get the same results which would make your results more reliable.