Answer:
The magnitude of the magnetic force on the particle is 67.86 N.
Step-by-step explanation:
Given that,
Charge,

Speed of particle, v = 68.4 m/s in +x direction
Magnetic field,

We need to find the magnitude of the magnetic force on the particle. The magnetic force is given by :

The magnitude of magnetic force on the particle is :

So, the magnitude of the magnetic force on the particle is 67.86 N.