Limits of accuracy

The Maths Habit

Write the error interval.

  1. p = 70, to the nearest 10

    65 ≤ p < 75

  2. q = 2.4, to 1 decimal place

    2.35 ≤ q < 2.45

  3. r = 13, to the nearest whole number

    12.5 ≤ r < 13.5

A bridge takes lorries up to 7.2 tonnes.

A lorry weighs 7 tonnes. Is it safe to cross?

Not for sure: it could be up to 7.5 tonnes

What is half of the rounding unit?

  1. Nearest 10

    5

  2. Nearest 100

    50

  3. Nearest whole number

    0.5

  4. 1 decimal place

    0.05

Lower bound
The smallest value that rounds to the number.
Upper bound
The value where numbers start rounding up to the next one.

A table is 90 cm long to the nearest 10 cm. Find the bounds.

80901008595
Bounds85 cm and 95 cm

A bag weighs 6 kg to the nearest kilogram. Find the bounds.

5675.56.5
Bounds5.5 kg and 6.5 kg

A table is 90 cm long to the nearest 10 cm. Find the bounds.

80901008595
Bounds85 cm and 95 cm

A river is 400 m wide to the nearest 100 m. Find the bounds.

300400500350450
Bounds350 m and 450 m

Limits of accuracy worksheet, page 1

Answer sheet

  1. A shelf is 80 cm to the nearest 10 cm. A gap is 84 cm to the nearest centimetre. Will the shelf definitely fit?

    No

  2. Two rods are each 6 cm to the nearest centimetre. What is the smallest their total length could be?

    11 cm

  3. A plank is 60 cm long to the nearest 10 cm. Could it be 55 cm? Could it be 65 cm?

    55 cm yes, 65 cm no

  1. A rope is 30 m long to the nearest 10 m. Find the lower and upper bounds.

    25 m and 35 m

  2. A parcel weighs 4.6 kg to 1 decimal place. Find the lower and upper bounds.

    4.55 kg and 4.65 kg

  3. A bolt is 7 cm long to the nearest centimetre. Which of these could be its length: 6.4 cm, 6.5 cm, 7.49 cm, 7.5 cm?

    6.5 cm and 7.49 cm
Exit tickets to print