A coin is flipped 12 times. it comes up heads 9 times.

Question

write the experimental probability as a percentage.

Answer 1

If you do the binomial expansion (x+y)^12 the coefficient of the x^9y^3 would give you the number of times you would get 9heads and 3 tails

Thus is 12C9 which is 12!/(12-9)!(9!) which equals

12!/3! x9!= 220

Total possible outcomes is 2^12

So probability is 220/2^12=.05371 which is 5.37%