The length of a plank of wood is 80cm to the nearest 1cm. What is the largest and smallest possible value for the actual length of the plank?

Bounds can be used when a value has been approximated. e.g. The length of a plank of wood is 80cm to the nearest 1cmThe lower bound is the smallest value that would round up to the estimated value. In this example, this means the smallest number that would still round up to give 80cm. This would be 79.5cm. This is because values lower than 79.5cm would round down (e.g. 79.4 or 79.49 would round down to 79cm to the nearest cm). Values (such a 79.51 or 79.6) that are greater than 79.5 are not the smallest possible value that round up.The upper bound is the smallest value that would round up to the next estimated value. In this example, this means the smallest value that will round up to 81cm. This will be 80.5cm. A value lower than this (e.g. 80.3 or 80.49) would round down to 80cm. A value higher than this (e.g. 80.51 or 80.8) would still round up to 81cm but would not be the lowest possible value that rounds up.One way to remember how to calculate bounds is to halve the degree of accuracy (In this example you would do 1cm/2 = 0.5cm) then you add this to the rounded value for the upper bound (80+0.5=80.5) and subtract it from the rounded value for the lower bound (80-0.5+79.5)Overall this means that the actual length of the plank could be between 79.5cm and 80.5cm.