Problem solving with rounding, estimation and bounds | Maths

Exit quiz

A quick estimate for a calculation is obtained from using ______ values, often rounded to 1 significant figure.

'approximate' ✓
Match each to the appropriate measure.

Height of a house

⇔

metres ✓

Mass of an dog

⇔

kilograms ✓

Time taken to eat your tea

⇔

minutes ✓

Distance from London to Dover

⇔

kilometres ✓

Area of a rugby pitch

⇔

$m^2$ ✓

Volume of a fish tank

⇔

$cm^3$ ✓
Which of the following are reasonable approximations?

The height of a tree $\approx$ 5 km

The distance between London and Manchester $\approx$ 300 km ✓

Area of a football pitch $\approx$ 7000 $m^2$ ✓

The length of a cats tail $\approx$ 0.03 m
Using estimation only which of the following is the correct answer to ${{106^2\times1.587}\over35.06}$

50.86004564

508.6004564 ✓

5086.004564

50860.04564

508600.4564
Estimate the value of ${23.87\times105.7}\over38.942$

'50' ✓
Andeep's dog is fed twice a day. Each meal weighs 175 g. A bag of food contains 7.5 kg. Estimate how many days the bag of food will last.

'20 days' ✓

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

Emphasise the infinite nature of a measurement.

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