How can you find k?

Question

X 1 2 3 4 5

p(x) 1/15 k/15 k/5 4/15 k/15

Answer 1

The sum of the probabilities must be equal to 1. Then,

1/15 + k/15 + k/5 + 4/15 + k/15 = 1

5/15 + 5k/15 = 1

1/3 + k/3 = 1

k/3 = 2/3

k = 2