Numbered disks are placed in a box and one disk is selected at random. If there are 6 red disks numbered 1through 6, and 4 yellow disks numbered 7 through 10, find the probability of selecting a yellow disk, given that the number selected is less than or equal to 3 or greater than or equal to 8.

Answer 1

there are 3 discs ≤ 3
there are 3 discs ≥ 8
3 of these 6 discs are yellow, so P(yellow) = 3/6