(i) Sum of probabilities = 0.4 + 0.4 + 0.2 = 1
Hence, given distribution is a probability distribution.
(ii) Sum of probabilities = 0.6 + 0.1 + 0.2 = 0.9 ≠ 1
Hence, the given distribution is not a probability distribution.
(iii) Here, one of the probability is – 0.1. which is negative.
Hence, this distribution is not probability distribution.