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Year 10 - Maths

Using upper and lower bounds practically

Rounding, estimation and bounds

Unit Summary

This unit explores the impact of upper and lower bounds on additive and multiplicative calculations.

Lesson Summary

You will learn to consider a context and decide whether it is suitable to use the upper or lower bound for each value in a calculation.

Key Notes

  • When considering safety contexts, you want to be able to guarantee safety limitations (weight of materials).
  • When considering costs, you may wish to know the maximum cost to you.
  • When training in sport, you may wish to know the time you need to beat in order to win a race.

Vocabulary To Learn

  • Upper bound: The upper bound for a rounded number is the smallest value that would round up to the next rounded value.
  • Lower bound: The lower bound for a rounded number is the smallest value that the number could have taken prior to being rounded.
  • Error interval: An error interval for a number x shows the range of possible values of x. It is written as an inequality a ≤ x < b

Common Mistakes To Avoid

  • For example if a measurement of 12 cm has been given to the nearest centimetre assuming the upper bound is 12.4 cm.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

When considering safety contexts, you want to be able to guarantee safety limitations (weight of materials). When considering costs, you may wish to know the maximum cost to you.

2. Use this key word in a maths sentence and explain it clearly. 'Upper bound'

The upper bound for a rounded number is the smallest value that would round up to the next rounded value. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: For example if a measurement of 12 cm has been given to the nearest centimetre assuming the upper bound is 12.4 cm. Correction: Emphasise the infinite nature of a measurement.

More Lessons In This Unit

Browse all guides in the Year 10 Maths guide library.