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No. You can start practising Error Intervals straight away without an account. A free account keeps your results across sessions, so you can see your progress on this topic over time.

Estimation, rounding and accuracy

Error Intervals

Q: What are the common mistakes in Error Intervals?

Treats truncating a number as equivalent to rounding it Writes both ends of an inequality as strict when at least one should be inclusive Truncates the boundary values instead of using the exact inequality endpoints

Q: How many Error Intervals practice questions are there?

There are 49 self-marking GCSE and IGCSE Maths questions on Error Intervals, written for AQA, Pearson, OCR, Pearson International GCSE Maths A (4MA1), Cambridge IGCSE Mathematics (0580), Cambridge IGCSE (9-1) Mathematics (0980) across Foundation and Higher and Extended tier. Each one is marked instantly and has a full worked solution.

49 self-marking GCSE and IGCSE practice questions on Error Intervals, written specifically for AQA, Pearson, OCR, Pearson International GCSE Maths A (4MA1), Cambridge IGCSE Mathematics (0580), Cambridge IGCSE (9-1) Mathematics (0980) across Foundation and Higher and Extended tier. Instant marking with full worked solutions on every question.

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Sample Error Intervals questions

A few of the 49 questions, from easier to harder. Choose your exam board and tier to practise them, with every answer marked.

Question 12 marksGrade 2
The length of a table is 110 cm, to the nearest cm. Write down the error interval for the length, using inequality notation.
Show the worked solution
Rounded to the nearest cm, the error interval is ±0.5: 109.5 ≤ length < 110.5. M1 (1 correct answer) A1 (both correct answers)
Question 22 marksGrade 4-5
A crowd size is rounded to the nearest 100, giving $4500$ . Write down the error interval for the true value, using inequality notation.
Show the worked solution
The true value could be anything from half a rounding unit below to half a rounding unit above the rounded value:

What are the common mistakes in Error Intervals?

When a pupil makes one of these on Revision Workshop, the marking engine names the mistake and explains it, instead of just marking the answer wrong.

Treats truncating a number as equivalent to rounding it
Treated the calculator display as a ROUNDED value (using a half-unit bound either side) instead of a TRUNCATED one - a truncated display simply cuts off further digits without rounding, so the true value could be anywhere from the shown value up to (but not reaching) one unit higher.
Writes both ends of an inequality as strict when at least one should be inclusive
Used a strict inequality at both ends, but the lower bound should be included ( $\leq$ ) since 15 itself rounds to 20
Truncates the boundary values instead of using the exact inequality endpoints
Made the lower bound strict ( $<$ ), but the truncated value itself IS a possible value of $x$

Quick answers about Error Intervals

How many Error Intervals practice questions are there?: There are 49 self-marking GCSE and IGCSE Maths questions on Error Intervals, written for AQA, Pearson, OCR, Pearson International GCSE Maths A (4MA1), Cambridge IGCSE Mathematics (0580), Cambridge IGCSE (9-1) Mathematics (0980) across Foundation and Higher and Extended tier. Each one is marked instantly and has a full worked solution.
Do I need an account to practise Error Intervals?: No. You can start practising Error Intervals straight away without an account. A free account keeps your results across sessions, so you can see your progress on this topic over time.