You toss a fair coin 4 times. What is the probability that: a. you get all Tails? b. you get at least one Head?

Answer 1

a) They probability of flipping a head = the probability of flipping a tails = (1/2) on any given flip with a fair coin.

Flipping a fair coin 4 times are 4 independent events. What happened before does not affect what happens next in this case.

So the probability of flipping four tails in a row = (1/2) × (1/2) × (1/2) × (1/2) = (1/2)^4 = 1/16.

b) the probability of getting at least one head = 1 - (the probability of getting 4 tails in a row) / 1 - (1/16) = 15/16.