Estimation and Approximation

The weight of a bag of potatoes is 25 kg, correct to the nearest kg.

What is smallest possible weight of the bag of potatoes?

• 24 kg

• 24.5 kg

• 25 kg

• 25.5 kg

The length of a line is 63 centimetres, correct to the nearest centimetre.

What the greatest possible length of the line?

• 62 cm

• 62.5 cm

• 64 cm

• 63.5 cm

A field is in the shape of a rectangle. The width of the field is 28 metres, measured to the nearest metre.

Work out the upper bound of the width of the field.

• 28 m

• 57 m

• 56 m

• 28.5 m

The number 90 has been rounded to 1 significant figure.

What is the lower boundary of the number?

• 90.5

• 100

• 95

• 85

The weight of a pram is 10 kg, correct to the nearest kg.

Find the greatest possible weight of the pram.

• 11 kg

• 10.4 kg

• 10.5 kg

• 9.5 kg

The length of a card is 20.5 cm to the nearest tenth of a cm.

The interval on the number line below shows all the possible real lengths of the card.

Which of the following is/are correct for the value of C and E?

[You can choose more than one possible answer]

• C = 20.40

• C = 20.45

• E = 20.60

• E = 20.55

A rectangular plot of land has sides with lengths of 38 m and 52 m correct to the nearest m.

Calculate the maximum possible values of the perimeter of the rectangle.

• 180 m

• 147 m

• 91 m

• 182 m

Hannah measures with a ruler that has marks every 0.1 cm. She says that the lengths of the side of a rectangle are 8.5 cm and 12 cm correct to 1 decimal place.

Calculate the minimum possible values of the perimeter of the rectangle.

• 20.4 cm

• 39.9 cm

• 40.6 cm

• 40.8 cm