Estimation

Maths

Accuracy and estimation

Estimate the total cost of 32 books at £178 each and 57 markers at £22.30 each.

Nothing, they just multiplied the original values

Rounded both values down and then multiplied.

Rounded both values to the nearest integer and then multiplied

Rounded both values to to 1 s.f. and then multiplied

Student A estimated that 23.5 x 91 = 1800. Student B estimated that 23.5 x 91.4= 2160. What did student B do?

Estimate the value of: 6.2 + 7.9 x 3.2 - 9.8

Because both values were rounded up meaning answer will be greater

Only one value was rounded up and so answer is only a little greater than the exact value

I estimated that 7.85 x 29 = 240. Why is my estimated answer more than my exact answer?

A classroom is measured 5.4 x 3.4 metres, measured to 1 d.p. Calculate the lower bound of the area of the room.

James ran a distance of 400m in a time of 25.2 seconds. The distance of 400m was measured to the nearest 10 metres. The time of 25.2 was measured to the nearest tenth of a second. Work out the upper bound James' average speed.

James ran a distance of 400m in a time of 25.2 seconds. The distance of 400m was measured to the nearest 10 metres. The time of 25.2 was measured to the nearest tenth of a second. Work out the lower bound James' average speed.

Carl measured the length and width of a rectangle. He measured the length to be 19cm correct to the nearest centimetre. He measured the width to be 20cm correct to the nearest 10cm. Calculate the lower bound for the area of this rectangle.

6 heights are listed, given to one decimal place: 4.6cm, 6.3cm, 9.8cm, 3.2cm, 5.7cm, 3.6cm. Work out the greatest possible mean.

A circle has an area of 130cm^2 to the nearest 10cm^2. Work out the upper bound of the radius. Give your answer to 3 d.p.

Estimation

Lesson outcome