A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is in which direction?

upward

Fleming left hand rule states that if we stretch our thumb forefinger and middle figure of our left hand perpendicular to each other in such a way that forefinger points the direction of magnetic field and middle figure points the direction of current and middle figure points the direction of current then thumb will represent the direction of force.