Question

Liliana has a bag of marbles. the bag contains 18 black, 15 red, 11 blue, and 8 white marbles. liliana randomly takes a red marble from the bag and leaves the marble on a table. what is the probability that she will next take a red or a white marble from the bag?

Answer 1

Since you took a red marble from the bag and didn't put it back, you now only have 14 red marbles to pick out of, and the total number of marbles i in your bag is only 51. Probability of choosing red or white is:
(14/51)  + (8/51) = 22/51