This is the question I am having difficult with. I really have no idea where to start.

Here's what I have gathered with the information provided:

Using the right hand rule, I've concluded v points along the x axis, the the force acting on the particle point along the z axis. Since the electron is under the influence of the magnetic field, and its radial acceleration is opposite in direction to the force, it will follow the path of a circle in the negative z direction. From here, I don't know where to go..

Thanks in advance.