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 - OCR - GCSE Maths - Question 8 - 2020 - Paper 1
Question 8
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 diagr... 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 - OCR - GCSE Maths - Question 8 - 2020 - Paper 1
Step 1
1. The probability for Tuesday's 'rains' branch is incorrect.
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Answer
Ella has indicated that the probability of it raining on Tuesday is 0.75, which is incorrect. The correct probability should be 0.25 based on the forecast.
Step 2
2. The probability for Tuesday's 'does not rain' branch is incorrect.
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Answer
As a result of the first error, the probability of 'does not rain' for Tuesday is also incorrect. It should be calculated as 1 - 0.25 = 0.75, but Ella shows it as just 0.35 instead.
Step 3
3. The branches of the tree diagram are not correctly representing the total probabilities.
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Answer
The sum of the probabilities on both branches for each day must equal 1. For Monday, Ella has 0.55 + 0.35 = 0.90, which does not equal 1. The correct would be 0.55 + (1 - 0.55) = 1.
