Hard projectile motion problem

[Sciencespy]

In the standing broad jump, one squats and then pushes off with the legs to see how far one can jump. Suppose the extension of the legs from the crouch position is 0.600 m and the acceleration achieved from this position is 1.25 times the acceleration due to gravity, g . How far can they jump? State your assumptions. (Increased range can be achieved by swinging the arms in the direction of the jump.)

 

[Baluncore]

Welcome to PF.
Is this homework?

Does the 1.25g acceleration take place vertically or maybe at 45°?
Arms forward on take-off will advance the centre of mass, but not necessarily give an increased distance unless they end up behind.
Swinging the arms in circles can change orientation while in the air. If the jumper was tall and landed flat on their back, lying across their track, they might go further. Do they have to land on their feet?