The probability that Chip will beat his friend is found by dividing the number of times he beats his friend by the total of the odds. So, we know that the odds against Chip beating his friend are 1:5, which means that the odds in favour Chip beating his friend are 5:1. Therefore, it comes like this:
5 (number of times he beats his friend) / 6 (total of the odds: 5+1)
