I think you're looking for Pascal's Triangle. let P = probability of 2 heads given 4 coins let omega = (x + y)^n # probability space let x = 50%

I think you're looking for Pascal's Triangle. let P = probability of 2 heads given 4 coins let omega = (x + y)^n # probability space let x = 50% # P(heads) let y = 50% # P(tails) let (n, k) = (4, 2) # 4 coins, 2 heads P = (n, k)(x )^2(y )^2 (4, 2)(50%)^2(50%)^2 (6 )(25%) (25%) # (4, 2) = 6; see link (6 )(6.25%) (37.5%) https://en.wikipedia.org/wiki/Pascal%27s_triangle https://en.wikipedia.org/wiki/Pascal%27s_triangle