Selection can be made in 5C2 = 10 ways, and the favorable ways for a, b such that a b < 4, areern5231 wrote:a and b are selected from the set {1,2,3,4,5}. What is the probability that ab<4?
1 & 2 and 1 & 3, only 2, order doesn't matter here
the required probability is 2/10 = [spoiler]1/5 = 0.2[/spoiler].
