An urn contains 1 black and 16 white balls. Balls are drawn at random, one at a time, until the black ball is selected. Each ball is replaced before the next ball is drawn. Find the probability that at least 24 draws are needed.

Consider a jar of marbles that contains 5 blue, 3 red, 8 green, and 7 yellow marbles. Select a marble at random and then replace it in the jar. Find the probability that you select a green marble for the first time on the first or third or fifth attempt.

A card is drawn at random out of a​ well-shuffled deck of 52 cards. Find the probability of drawing a face card or ace.

Find the probability of getting at most 2 heads in the flipping of three coins.