Final answer:
The scale reading will be 150 N.
Step-by-step explanation:
The scale reading in this scenario can be calculated by considering Newton's second law: F = ma. We can first find the force acting on the person by multiplying their mass (50 kg) by the acceleration of the elevator (3.0 m/s²). This gives us a force of 150 N.
Since the person and the elevator are in contact with each other, the scale will exert an equal and opposite force on the person. Therefore, the scale reading will be equal to the force exerted on the person, which is 150 N.
Therefore, the scale will read 150 N in this scenario.