Bag A has 5 red and 7 blue counters. Bag B has 4 green and 5 yellow counters. Choose one counter at random from each bag, independently. What is the probability of red and green?
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Answer: 275
Multiply independent probabilities.
125×94=275.
Example 2
A bag has 8 red and 2 blue counters. Two counters are drawn at random without replacement. What is the probability both are red?
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Answer: 4528
After one red is removed, 7 red counters remain among 9.
Multiply 54×97=4528.
Example 3
A bag has 8 red and 2 blue counters. Draw a counter, replace it and mix, then draw again. What is the probability of exactly one red counter across the two draws?
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Answer: 258
Either red then blue, or blue then red.
2×54×51=258.
Combined events and sampling without replacement practice | Year 9 | Ascent Arcade