A bag contains 5 red counters and 3 blue counters. Two counters are taken at random from the bag without replacement. Find the probability that both counters are the same colour.
Answer and explanation
Correct answer: C.
- Step 1: Total counters initially . Compute the probability of drawing two red counters without replacement: .
- Step 2: Compute the probability of drawing two blue counters without replacement: .
- Step 3: Add the mutually exclusive probabilities and simplify: .
Answer
.
Why not the others: is the probability of drawing one red and one blue counter in that order; is only the probability of two red counters; assumes replacement or equal probabilities.
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