Let us calculate the  probability of getting 1 head

n = 4 indicating a maximum of four heads possible
x = 1 indicating that we get exactly one head
p = 1/2 indicating that there is a 50% probability of getting a head
q = 1/2 indicating that there is a 50% probability of not getting a head

Substituting these in the equation above we get,

f(x) = [ 4! / ( 1! x (4-1)! ] x (1/2) ¹ x  (1/2)^4-1

       = [ 24 / (  1 x 6 ) ] x 1/2  x 1/8       

       =  4 x 1/2  x 1/8       

       =  4/16    

Similarly by substituting the other values of x, i.e. 0,2,3 and 4, we can also find the probabilities of getting 0,2,3 and 4 heads, which turn out to be 1/16, 6/16, 4/16, and 1/16.