A carpenter measures the length, k metres, of a piece of wood - OCR - GCSE Maths - Question 18 - 2021 - Paper 3
Question 18
A carpenter measures the length, k metres, of a piece of wood.
They write
3.35 < k < 3.45.
(a) Put rings around all possible values of k in the list below.
3.349... show full transcript
Worked Solution & Example Answer:A carpenter measures the length, k metres, of a piece of wood - OCR - GCSE Maths - Question 18 - 2021 - Paper 3
Step 1
Put rings around all possible values of k in the list below
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Answer
In the range 3.35 < k < 3.45, we identify the values of k that fall within this interval:
3.349: This is less than 3.35, so it should not be circled.
3.39: This is within the interval, so it should be circled.
3.44: This is also within the interval, so it should be circled.
3.45: This is equal to 3.45 and not included in the interval, so it should not be circled.
3.55: This is greater than 3.45, so it should not be circled.
Step 2
Explain how you know that she is incorrect.
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Answer
The carpenter is incorrect because if 3.4 metres is measured to the nearest centimetre, it can actually lie within the range of:
3.345 m≤k<3.455 m
This means k could be less than 3.35 or greater than 3.45, which does not satisfy the original measurement 3.35 < k < 3.45.
Step 3
Complete the interval for 3.4 m, correct to the nearest centimetre.
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Answer
The interval for 3.4 m, correct to the nearest centimetre, is: