A bag holds 3 red, 3 blue and 5 green counters. Two are taken at random without replacement. What is the probability that neither is red?
Answer and explanation
Correct answer: B. 28/55
- Step 1: Non-red counters: 8 of 11. First: 8/11; second: 7/10. Step 2. 8/11 x 7/10 = 28/55. Answer: 28/55. Why not the others: 64/121 uses replacement; 52/55 is the chance of at least one non-red counter; 56/121 keeps 11 as the second denominator.
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