Calculate the probability of an event given counts or proportions within a sample space.
87 original probability questions in the SAT Ranker bank, with instant scoring and an Elo-based rank once you sign up. Below are a few free samples with full explanations.
A bag contains 5 red, 3 blue, and 2 green marbles. If one marble is drawn at random, what is the probability that it is NOT blue?
There are 10 marbles total and 3 are blue, so 7 are not blue. Probability = 7/10 = 0.7.
A bag contains 13 red, 30 blue, 5 green, 2 yellow marbles. If one marble is drawn at random, what is the probability that it is NOT red?
There are 50 marbles total and 13 are red, so 37 are not red. Probability = 37/50 = 0.74.
A bag contains 40 red, 13 blue, 24 green, 23 yellow marbles. If one marble is drawn at random, what is the probability that it is NOT red?
There are 100 marbles total and 40 are red, so 60 are not red. Probability = 60/100 = 0.6.
A bag contains 13 red, 14 blue, 10 green, 13 yellow marbles. If one marble is drawn at random, what is the probability that it is NOT green?
There are 50 marbles total and 10 are green, so 40 are not green. Probability = 40/50 = 0.8.
A bag contains 10 red, 1 blue, 1 green, 8 yellow marbles. If one marble is drawn at random, what is the probability that it is NOT yellow?
There are 20 marbles total and 8 are yellow, so 12 are not yellow. Probability = 12/20 = 0.6.