you toss a coin 30 times and get 12 heads.

Question

the experimental probability heads is ?

Answer 1

probability = # ways what you want happens / # ways everything happens

# ways to get 12 heads on 30 tosses = 30!/(12!*18!) = 86493225

(on your calculator that should be the nCr button or the C(x,y) button)

# ways to flip 30 coins = 2^30 = 1073741824

P(exactly 12 heads on 30 tosses) = 86493225 / 1073741824 = about 0.08055309299