Final answer:
Using the right-hand rule, with the thumb pointing upwards in the opposite direction of the electron's motion, the magnetic field towards the right will be directed into the room.
Step-by-step explanation:
To determine the direction of the magnetic field created by an electron moving from the ceiling to the floor, you use the right-hand rule. Point your thumb downwards in the direction of the electron's velocity (recall that electrons have a negative charge, so the "current" is upwards in the opposite direction of the electron's motion). The fingers of your right hand will then curl into your palm. According to this rule, the magnetic field at a position to your right will be directed into the room (perpendicular to the right-hand wall and away from you).
It is important to consider that the direction of the conventional current is opposite to the motion of electrons due to their negative charge. By pointing your right-hand thumb in the opposite direction (upwards) of the electron's motion, your fingers will curl and point into the room when your hand is positioned to your right.