Work Step by Step
Using the right-hand rule, if the charge were moving straight out of the page then we can wrap our hand in a coil with our thumb pointing towards us (since the direction of the velocity of the particle is again, coming out of the page and right at us). Now, the coil that our right hand makes is in the counterclockwise direction, and therefore at the point listed in the problem the direction of the magnetic field is downward. NOTE: If in this problem the particle had a negative charge the direction of the magnetic field would be upward. But that is not the case since the particle listed is a positive charge. The answer to this specific problem is down.