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A weather forecast says • the probability that it will rain on Monday is 0.55 and • the probability that it will rain on Tuesday is 0.25 Ella draws a tree diagram to show this information - OCR - GCSE Maths - Question 22 - 2020 - Paper 1
Question 22
A weather forecast says • the probability that it will rain on Monday is 0.55 and • the probability that it will rain on Tuesday is 0.25 Ella draws a tree dia... show full transcript
Worked Solution & Example Answer:A weather forecast says • the probability that it will rain on Monday is 0.55 and • the probability that it will rain on Tuesday is 0.25 Ella draws a tree diagram to show this information - OCR - GCSE Maths - Question 22 - 2020 - Paper 1
Step 1
Write down three errors that Ella has made with her tree diagram.
Answer
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The probability of not raining on Monday should be calculated as 1 - 0.55 = 0.45, but Ella has written 0.35.
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The probabilities for Tuesday's outcomes should add up to 1. She has written 0.25 for raining and 0.75 for not raining, which is correct. However, she should also ensure that the branch for Monday reflects the correct probabilities.
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The tree diagram does not properly connect the probabilities for Monday to Tuesday. It should display the outcomes of Tuesday under each Monday outcome (i.e., 'rains' and 'does not rain').