A bag contains red, blue and green counters. Three counters are taken at random without replacement. What is the probability that all three are different colours?
Answer and explanation
Correct answer: A.
- Step 1: Calculate the total number of equally likely ways to select counters from total counters without replacement: .
- Step 2: Compute the number of favourable outcomes where exactly one counter of each colour (red, blue, green) is chosen: .
- Step 3: Divide favourable outcomes by total outcomes and simplify: .
Answer
.
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