Question

What is the probability of flipping heads three times in a row?
1/4
1/6
1/8
1/12

Answer 1

It'll be 1/8 because 0.5^3 = 12.5%
On each consecutive flip, the probability decreases by 1/2 of previous probability.
50% on first flip because a coin toss always has 1/2 chance due to heads and tails sides of the coin.
So second flip would be 1/4 or 25%. The third flip in a row will be the 1/2 of that 1/4 or 1/8 which is 12.5% chance.

Answer 2

so an easier way to do this is do 0.5^n where n is the number of coin flips.