Question
A bag contains 10 white balls, 5 black balls and 5 red
balls. Two balls are drawn at random. What is the probability that at least one of them is red?Solution
Total balls = 10 + 5 + 5 = 20
Non-red balls = 10 + 5 = 15
Required probability = 1 - (15/20) × (14/19)
= 1 - (210/380)
= 1 - (21/38)
= 17/38
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