Paper 22 Q23IGCSE 0580 May/June 2023

Question

23 Bag A and bag B each contain red sweets and yellow sweets. Anna picks a sweet at random from bag A. Ben picks a sweet at random from bag B. The probability that Anna picks a red sweet is 2/5. The probability Anna and Ben both pick a yellow sweet is 1/10. Find the probability that Anna and Ben both pick a red sweet.

This question tests your ability to work with independent probability events and use given information to find unknown probabilities. You need to use the multiplication rule for independent events and set up equations from the given conditions.

Step-by-Step Solution

Key Takeaway

For independent events, multiply individual probabilities together and use the fact that probabilities of all outcomes sum to 1.

Common Mistakes

Adding probabilities instead of multiplying them - remember that for independent events happening together, you multiply the individual probabilities
Forgetting that P(red) + P(yellow) = 1 for each bag, so you can find one probability if you know the other

Exam Tip

Always check your final answer makes sense - probabilities must be between 0 and 1, and both picking red should be less likely than just Anna picking red.

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