Question 982999
z = (x-mu)/sigma



z = (83-86)/4



z = -0.75



Use a table like <a href="https://www.stat.tamu.edu/~lzhou/stat302/standardnormaltable.pdf">this one</a> to find that P(Z < -0.75) = 0.22663



So, P(X < 83) = 0.22663