Year 8 Measurement Answers

Name:

Date:

📐 Part 1: Multiple Choice Answers

1. What is 2.5 kilometres in metres?

Answer: C) 2500 metres

Solution: 2.5 km × 1000 m/km = 2500 m

2. Which unit is most appropriate for measuring the length of a pencil?

Answer: B) Centimetres

Explanation: Pencils are typically 15-20 cm long, making centimetres the most practical unit.

3. A rectangular garden has a length of 8 metres and width of 5 metres. What is its area?

Answer: A) 40 square metres

Solution: Area = length × width = 8 m × 5 m = 40 m²

4. Convert 3.2 kilograms to grams:

Answer: D) 3200 grams

Solution: 3.2 kg × 1000 g/kg = 3200 g

🔢 Part 2: Calculation Answers

5. Calculate the perimeter of a triangle with sides 7 cm, 9 cm, and 12 cm.

Answer: 28 cm

Working:

Perimeter = sum of all sides

P = 7 cm + 9 cm + 12 cm = 28 cm

6. A circle has a radius of 6 metres. Calculate its area. (Use π = 3.14)

Answer: 113.04 m²

Working:

Area of circle = πr²

A = 3.14 × 6² = 3.14 × 36 = 113.04 m²

7. Convert the following measurements:

a) 450 centimetres = 4.5 metres (450 ÷ 100)

b) 2.8 litres = 2800 millilitres (2.8 × 1000)

c) 750 grams = 0.75 kilograms (750 ÷ 1000)

🧮 Part 3: Problem Solving Answers

8. Sarah is painting a rectangular wall that is 4.2 metres long and 2.8 metres high. If one litre of paint covers 8 square metres, how much paint does she need?

Answer: 1.47 litres (or approximately 1.5 litres)

Working:

Step 1: Calculate wall area = 4.2 m × 2.8 m = 11.76 m²

Step 2: Calculate paint needed = 11.76 m² ÷ 8 m²/litre = 1.47 litres

9. A school playground is in the shape of a rectangle measuring 45 metres by 30 metres. What is the cost to fence the entire perimeter if fencing costs $12 per metre?

Answer: $1800

Working:

Step 1: Calculate perimeter = 2(45 + 30) = 2(75) = 150 metres

Step 2: Calculate cost = 150 metres × $12/metre = $1800

10. A cylindrical water tank has a diameter of 3 metres and height of 2.5 metres. Calculate its volume. (Use π = 3.14)

Answer: 17.66 cubic metres

Working:

Step 1: Find radius = diameter ÷ 2 = 3 ÷ 2 = 1.5 metres

Step 2: Volume of cylinder = πr²h

Step 3: V = 3.14 × (1.5)² × 2.5 = 3.14 × 2.25 × 2.5 = 17.66 m³