NumberDeep Dive

Finding Bounds

Part of Bounds & Error IntervalsGCSE Mathematics

This deep dive covers Finding Bounds within Bounds & Error Intervals for GCSE Mathematics. Revise Bounds & Error Intervals in Number for GCSE Mathematics with 14 exam-style questions and 5 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 3 of 6 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 3 of 6

Practice

14 questions

Recall

5 flashcards

Finding Bounds

1 Identify the degree of accuracy (1 d.p., nearest 10, etc.)
2 Find HALF the accuracy interval
3 LB = value − half interval, UB = value + half interval
Rounded to... Half interval Example: 50
Nearest whole number ±0.5 LB=49.5, UB=50.5
1 decimal place ±0.05 LB=49.95, UB=50.05
Nearest 10 ±5 LB=45, UB=55
Nearest 100 ±50 LB=0 (can't go negative if context), UB=100

Keep building this topic

Read this section alongside the surrounding pages in Bounds & Error Intervals. That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Bounds & Error Intervals

A length is 240 cm to the nearest 10 cm. What is the lower bound of the length?

  • A. 230 cm
  • B. 235 cm
  • C. 239 cm
  • D. 245 cm
1 markfoundation

A mass m is 45 kg to the nearest kilogram. Write down the error interval for m using inequality notation.

2 marksfoundation

Quick Recall Flashcards

Max of A ÷ B
Max = UB(A) ÷ LB(B). Big top, small bottom = big answer
Rationalising
Remove surd from denominator: 1/√2 = √2/2

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