Our problem involves probability. One thing that we must take note of probabilities is that the higher the number of a certain thing is, the higher probability of it happening. For example, in a lottery the higher the number of of tickets that you will buy the higher the chances of you winning the lottery.
Now let us talk about the basic formula of the probability of an event happening. The probabilty of an event happening is just the ratio of the number of a certain outcome to the total number of outcomes. Presenting it as an equation we get: