When two events occur, there are several possible outcomes.
For example, when a coin is thrown, it can land heads up (H) or tails up (T).
So when two coins are thrown, the possible outcomes are:
H H
H T
T H
T T
There are four possible outcomes.
So the probability of getting two heads, P(HH) = 1/4
The probability of getting one head, P(H) = 2/4 = 1/2 because we can either have HT, or TH.
Let's get started on the questions now.
It's important to make carefully organised, systematic lists when determining all the outcomes and not just write out the outcomes randomly.