Primary 3 Mathematics Measurement Quiz

Primary 3 Mathematics Quiz - Measurement: Answer Key

Total Marks: 40 marks

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Section A: Multiple Choice (1 mark each)

1. Answer: (C) 8.7 cm

The pencil starts at 0 cm and ends at the 7th millimetre mark after 8 cm. Each small mark represents 1 mm, which equals 0.1 cm. Counting: 8 cm + 7 mm = 8 cm + 0.7 cm = 8.7 cm.

Teaching note: When measuring, always check where the object starts (not always at 0) and read the scale carefully. Each centimetre has 10 millimetres, so 7 mm = 0.7 cm.

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2. Answer: (B) 1 kg 550 g

Step-by-step working:

• Start: 3 kg 250 g
• Used: 1 kg 800 g

Since 250 g < 800 g, we need to borrow 1 kg = 1000 g:

• 3 kg 250 g = 2 kg 1250 g
• Subtract: 2 kg 1250 g − 1 kg 800 g = 1 kg 550 g

Common mistake: Students often subtract 250 − 800 directly and get confused. Always borrow from kilograms when grams are insufficient.

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3. Answer: (B) 506 cm

Step-by-step working:

• 5 m = 5 × 100 cm = 500 cm
• 6 cm = 6 cm
• Total: 500 cm + 6 cm = 506 cm

Key concept: 1 metre = 100 centimetres. Convert metres to centimetres first, then add the remaining centimetres.

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4. Answer: (A) 3 ℓ 750 mℓ

Step-by-step working:

• Start: 4 ℓ 500 mℓ
• Poured out: 750 mℓ

Since 500 mℓ < 750 mℓ, borrow 1 ℓ = 1000 mℓ:

• 4 ℓ 500 mℓ = 3 ℓ 1500 mℓ
• Subtract: 3 ℓ 1500 mℓ − 750 mℓ = 3 ℓ 750 mℓ

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5. Answer: (B) 10 kg

Step-by-step working:

• One packet: 2 kg 500 g
• Four packets: 4 × 2 kg 500 g

Method: Double twice

• 2 × 2 kg 500 g = 5 kg
• 2 × 5 kg = 10 kg

Alternative: Convert to grams: 2500 g × 4 = 10000 g = 10 kg.

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Section B: Short Answer (2 marks each)

6. Answer: 13.5 cm (or 13 cm 5 mm)

Step-by-step working:

• Ribbon starts at: 2 cm
• Ribbon ends at: 15.5 cm (or 15 cm 5 mm)
• Length = 15.5 cm − 2 cm = 13.5 cm

Key concept: When an object does not start at 0, subtract the starting position from the ending position. This is called the difference method.

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7. Answer: 3450 m

Step-by-step working:

• 3 km = 3 × 1000 m = 3000 m
• 450 m = 450 m
• Total: 3000 m + 450 m = 3450 m

Key concept: 1 kilometre = 1000 metres. Always convert the larger unit first.

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8. Answer: 1 ℓ 400 mℓ

Step-by-step working:

• Start: 2 ℓ 250 mℓ
• Drank: 850 mℓ

Borrow 1 ℓ = 1000 mℓ:

• 2 ℓ 250 mℓ = 1 ℓ 1250 mℓ
• Subtract: 1 ℓ 1250 mℓ − 850 mℓ = 1 ℓ 400 mℓ

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9. Answer: 400 g

Step-by-step working:

• Total mass: 1 kg 200 g = 1200 g
• Number of books: 3
• Mass of one book: 1200 g ÷ 3 = 400 g

Teaching note: Convert to a single unit (grams) before dividing. 1 kg = 1000 g, so 1 kg 200 g = 1000 g + 200 g = 1200 g.

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10. Answer: 210 cm

Step-by-step working:

• Convert to single unit: 8 m 40 cm = 800 cm + 40 cm = 840 cm
• Divide by 4: 840 cm ÷ 4 = 210 cm

Check: 210 cm × 4 = 840 cm = 8 m 40 cm ✓

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11. Answer: 46 cm

Step-by-step working:

• Perimeter of rectangle = length + width + length + width
• = 2 × (length + width)
• = 2 × (15 cm + 8 cm)
• = 2 × 23 cm
• = 46 cm

Formula: Perimeter of rectangle = $2 \times (l + w)$ or $2l + 2w$

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12. Answer: 300 m

Step-by-step working:

• Perimeter of field = 2 × (50 m + 25 m) = 2 × 75 m = 150 m
• Two rounds: 2 × 150 m = 300 m

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13. Answer: 4000 m

Step-by-step working:

• 1 km = 1000 m
• 4 km = 4 × 1000 m = 4000 m

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14. Answer: 9 ℓ 0 mℓ (or 9 ℓ)

Step-by-step working:

• Full capacity: 12 ℓ
• Filled to: 3/4 of capacity
• Water in tank: 3/4 × 12 ℓ = (12 ℓ ÷ 4) × 3 = 3 ℓ × 3 = 9 ℓ

Teaching note: Fraction 3/4 means divide into 4 equal parts, then take 3 parts. 12 ÷ 4 = 3, then 3 × 3 = 9.

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15. Answer: 1 ℓ 200 mℓ

Step-by-step working:

• Volume in Container A: 1 ℓ 200 mℓ
• When poured into Container B (same shape/size scale), the reading will be identical: 1 ℓ 200 mℓ

Key concept: Volume is conserved when liquid is poured between containers. The reading depends only on the amount of liquid, not the container (assuming same scale markings).

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Section C: Problem Solving (4 marks each)

16. (a) Answer: 3 km 500 m [2 marks]

Step-by-step working:

• House to Library: 1 km 250 m
• Library to School: 800 m
• School to House: 1 km 450 m

Convert all to metres:

• 1 km 250 m = 1250 m
• 800 m = 800 m
• 1 km 450 m = 1450 m

Total: 1250 m + 800 m + 1450 m = 3500 m = 3 km 500 m

Mark allocation: [1] for correct method/conversion; [1] for final answer with correct units.

(b) Answer: 10.00 a.m. (or 10 a.m.) [2 marks]

Step-by-step working:

• Start time: 9.15 a.m.
• Duration: 45 minutes
• End time: 9.15 a.m. + 45 min = 10.00 a.m.

Mark allocation: [1] for correct method; [1] for correct time notation.

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17. (a) Answer: 12 loaves [2 marks]

Step-by-step working:

• Total flour: 3 kg = 3000 g
• Flour per loaf: 250 g
• Number of loaves: 3000 g ÷ 250 g = 12 loaves

Method: 250 × 4 = 1000 (1 kg), so 250 × 12 = 3000 (3 kg). Mark allocation: [1] for conversion or correct method; [1] for final answer.

(b) Answer: 0 g (no flour left over) [2 marks]

Step-by-step working:

• Flour used: 12 × 250 g = 3000 g = 3 kg
• Flour available: 3 kg
• Left over: 3000 g − 3000 g = 0 g

Mark allocation: [1] for method (multiplication or recognition of exact division); [1] for final answer.

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18. (a) Answer: 60 m [2 marks]

Step-by-step working:

• Perimeter of garden = 2 × (18 m + 12 m)
• = 2 × 30 m
• = 60 m

Mark allocation: [1] for correct formula/application; [1] for correct calculation.

(b) Answer: 16 m [2 marks]

Step-by-step working:

• Pond is a square with side 4 m
• Fencing needed = perimeter of pond = 4 × 4 m = 16 m

Mark allocation: [1] for identifying square perimeter formula; [1] for correct calculation.

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19. (a) Answer: 25 cups [2 marks]

Step-by-step working:

• Total water: 5 ℓ = 5000 mℓ
• Cup size: 200 mℓ
• Number of cups: 5000 mℓ ÷ 200 mℓ = 25 cups

Method: 200 × 25 = 5000, or 5000 ÷ 200 = 50 ÷ 2 = 25. Mark allocation: [1] for conversion to same units; [1] for correct division and answer.

(b) Answer: 0 mℓ [2 marks]

Step-by-step working:

• Water used: 25 × 200 mℓ = 5000 mℓ = 5 ℓ
• Water available: 5 ℓ = 5000 mℓ
• Left over: 5000 mℓ − 5000 mℓ = 0 mℓ

Mark allocation: [1] for method showing water used equals total; [1] for final answer.

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20. (a) Answer: 80 kg [2 marks]

Step-by-step working:

• Total mass: 640 kg
• Number of sacks: 8
• Mass per sack: 640 kg ÷ 8 = 80 kg

Method: 8 × 80 = 640, or 640 ÷ 8 = (640 ÷ 2) ÷ 4 = 320 ÷ 4 = 80. Mark allocation: [1] for correct division method; [1] for correct answer.

(b) Answer: 2 sacks [2 marks]

Step-by-step working:

• Maximum load: 800 kg
• Current load: 640 kg
• Remaining capacity: 800 kg − 640 kg = 160 kg
• Mass per sack: 80 kg (from part a)
• Additional sacks: 160 kg ÷ 80 kg = 2 sacks

Alternative method: 800 ÷ 80 = 10 sacks maximum; currently 8; so 10 − 8 = 2. Mark allocation: [1] for finding remaining capacity or maximum sacks; [1] for final answer.

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END OF ANSWER KEY