Use the formula for the probability of the complement of an event. A coin is flipped 4 times. What is the probability of getting at least 1 head? (Enter your probability as a fraction.)

Question

Addition & Complement Rule

Answer 1

The probability of getting at least 1 head is the compliment of the probability of getting 0 heads.

That is, if the outcomes of the experiment can be {0,1,2,3,4}, It is easier to compute 1 - P(x = 0) than it is to compute P(x = 1) + P(x = 2) + P(x = 3) + P(x = 4). Normally we should be told that the probability of getting a head on a given throw is 0.5. Assume that. Then the probability of getting 0 heads is the probability of getting 4 tails which is (0.5)^4 = 1/16. Each toss is independent and this is a binomial experiment.