0.506 m/s^2
Given the arrangement of rope and the man, he's effectively suspended by a rope from a frictionless pulley. So he's pulling the rope with a force of 371 n causing him to be pulled upwards by his arms. Additionally, the rope goes up to the pulley and back down to the man causing an additional 371 n of force pulling him upwards. So the total force being used to lift the man is 742 n.
Additionally, the man is being pulled downwards by gravity at 9.80 m/s^2. And since he masses 72.0 kg, the downward force in newtons is 72.0 kg * 9.80 m/s^2 = 705.6 n downward.
So the total force being exerted on the man is
742 n - 705.6 n = 36.4 n
To calculate his acceleration, simply divide the number of newtons applied by his mass.
36.4 kg m/s^2 / 72.0 kg = 0.505556 m/s^2
And round to 3 significant figures.
0.505556 m/s^2 = 0.506 m/s^2
