Question

72 red and blue chairs in a class. The chair is selected at random from the class and the probability of selecting a blue chair is 2/3. If 4 red chairs and 2 blue chairs are taking out from the class, find the probability of selecting a red chair at random.​

Answer 1

After 4 red chairs and 2 blue chairs are taken out from the class, there are 72 - 4 - 2 = 66 chairs remaining. Of these 66 chairs, 72 * 2/3 - 2 = 46 chairs are blue. Therefore, the probability of selecting a red chair at random is (66 - 46) / 66 = 20/66 = 5/16.