Explanation:
Divide the frequency numbers by their total to get the relative frequency. Plot that on your graph.
P(0 heads) = 4/80 = 0.05
P(1 head) = 8/80 = 0.10
P(2 heads) = 36/80 = 0.45
P(3 heads) = 20/80 = 0.25
P(4 heads) = 12/80 = 0.15
