Adartboard has 8 sections of equal area. the letters represent colors red (r), yellow (y), blue (b), and green (g). complete the probability distribution for a dart that hits the board at a random location.

red: ?
yellow: 3/8
green: 3/8
blue: 1/8

Since the sum of all probabilities of all all elementary events will always be equal to 1. Furthermore, the probabilities of all mutually exclusive set of events that is part of the entire sample space will always be total of 1.

So in the problem, the answer is 1/8.
1/8 for red + 3/8 for green + 3/8 for yellow + 1/8 for blue = 8/8 or 1.