This introduction covers The Hidden Range 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 1 of 7 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
The Hidden Range
If someone says they're "180 cm tall" (to nearest cm), they could actually be anywhere from 179.5 cm to 180.5 cm! When a value is rounded, there's always a hidden range of possible values - that's what bounds are about. This matters in engineering where precision is critical.
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 mass m is 45 kg to the nearest kilogram. Write down the error interval for m using inequality notation.
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