Suppose an experiment consists of tossing two fair coins. What are the odds against both of them landing on heads?

Question

Suppose an experiment consists of tossing two fair coins. What are the odds against both of them landing on heads? 

3:1

1:4

1:3

4:1

Answer 1

P(both heads) = 1/4
P(not both heads) = 3/4
O(AGAINST both heads) = 3:1 because this is P(losing) divided by P(winning) where winning is both heads.