Answer:
[tex]B = 1.464*10^{-4}T[/tex] or [tex]146.4\mu T[/tex].
Explanation:
The right hand rule tells us that to produce a magnetic force directed towards west, the magnetic field must point straight up from the plane, and therefore [tex]v[/tex] and [tex]B[/tex] are perpendicular to each other and hence
[tex]F = q (v\times B) = qvB[/tex]
Solving for [tex]B[/tex] we get
[tex]B = \dfrac{F}{qv}[/tex]
putting in [tex]F = 8.9*10^{-18}N[/tex], [tex]q = 1.6*10^{-19}C[/tex], and [tex]3.8*10^{5}m/s[/tex] we get
[tex]B = \dfrac{8.9*10^{-18}N}{(1.6*10^{-19}C)(3.810^{5}m/s)}[/tex]
[tex]\boxed{B = 1.464*10^{-4}T.}[/tex]
which is also 146.4 micro Teslas.
