L

Upper and Lower Bounds

Measurements

  • Upper and lower bounds are a measure of accuracy

  • For example, the width of a postcard is given as 8cm to the nearest cm

  • The actual width of the postcard could be anything between 7.5cm and 8.5cm

  • 7.5cm is called the lower bound

  • 8.5cm is called the upper bound

In calculations

  • To find the overall upper and lower bounds of the answer to a calculation use these rules

Answer help

  • If you’re answering questions about upper and lower bounds, it’s a good idea to write out the upper bound and lower bound for all values given in the question before
  • To work out the lower bound for a-b you need to use the lower bound for a and the upper bound for b
  • Different values might be given to different degress of accuracy
  • The length of the roll is correct to 2 significant figures or to the nearest 10cm
  • The length of the piece cut off is correct to the nearest cm
  • Be really careful when you’re working out your upper and lower bounds