Answer
The scale will read more than 600 N just before the student leaves the scale.
Work Step by Step
The scale measures the net downward force exerted on the student, so if the student stands still, the scale only measures the force gravity exerts on them (also known as their weight). If the student jumps, however, they exert an additional downward force that the scale measures as a number above the original weight of 600 N.
