According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction.
In this scenario, the large magnet exerts a force of 3.00 N on the bar magnet. Therefore, the bar magnet will exert an equal and opposite force of 3.00 N on the large magnet.
So, the force that the bar magnet exerts on the large magnet is 3.00 N in the opposite direction.