Chapter 9 Practice Paper: Perimeter, Area, Volume and Surface Area — mark scheme
Secondary 1 · Lower Secondary Mathematics (G2 / G3)
Mark scheme
Perimeter, Area, Volume and Surface Area
Chapter 9 Practice Paper · Maximum mark: 30
Notes for markers
- Award one mark for each point marked [1], up to the marks shown for the part.
- Accept answers worded differently that show the same understanding.
- Units are required where the answer line shows one. ecf: allow an error carried forward.
Section A: Multiple-choice questions[10 marks]
| Question | Answer | |
|---|---|---|
| 1 | CArea = base × height, so the height is 36 ÷ 9 = 4 cm. The slanted sides are not involved. | 1 |
| 2 | A42 = ½ × 14 × height, so the height is 42 × 2 ÷ 14 = 6 cm. | 1 |
| 3 | DPerimeter = 2 × (7 + 3) = 20 cm. The value 21 cm² would be the area. | 1 |
| 4 | B72 = ½ × (10 + 14) × h = 12h, so h = 72 ÷ 12 = 6 cm. | 1 |
| 5 | CVolume = 3 × 3 × 3 = 27 cm³ — and volumes always carry cubic units. | 1 |
| 6 | AVolume of a prism = cross-section area × length = 18 × 12 = 216 cm³. | 1 |
| 7 | DSurface area = 2 × (5 × 4 + 5 × 3 + 4 × 3) = 2 × (20 + 15 + 12) = 94 cm². | 1 |
| 8 | B1 m = 100 cm, so 1 m³ = 100 × 100 × 100 = 1 000 000 cm³, and 2.5 m³ = 2 500 000 cm³. | 1 |
| 9 | AVolume = pi × r² × h = (22/7) × 49 × 12 = 1 848 cm³. | 1 |
| 10 | CArea = 8 × 3 = 24 m², and the cost is 24 × $2.50 = $60. | 1 |
Section B: Structured questions[20 marks]
| Question | Answer and marking points | Marks |
|---|---|---|
| 1(a) | 12 × 8 = 96 m² [1] | 1 |
| 1(b) | 5 × 3 = 15 m² [1] | 1 |
| 1(c) | 96 - 15 = 81 m² [1] | 1 |
| 1(d) | Cost = 81 × 12 = $972
| 2 |
| Total for Question 1 | 5 | |
| 2(a) | Length = (x + 4) cm, and the area equation is x(x + 4) = 45.
| 2 |
| 2(b) | Try x = 5: 5 × 9 = 45 ✓. So x = 5. (x = 6 gives 6 × 10 = 60, too big; x = 4 gives 4 × 8 = 32, too small.)
Any systematic search is accepted; the check of neighbouring values strengthens the argument. | 2 |
| 2(c) | 2 × (5 + 9) = 28 cm [1] | 1 |
| Total for Question 2 | 5 | |
| 3(a) | 6 × 4 × 2.5 = 60 cm³ [1] | 1 |
| 3(b) | Surface area = 2 × (6 × 4 + 6 × 2.5 + 4 × 2.5) = 2 × (24 + 15 + 10) = 2 × 49 = 98 cm².
| 2 |
| 3(c) | Box volume = 12 × 12 × 10 = 1 440 cm³, and 1 440 ÷ 60 = 24 blocks.
Award full marks for a justified arrangement argument; the volume ratio must divide exactly, which it does here. | 2 |
| Total for Question 3 | 5 | |
| 4(a) | Volume = pi × r² × h = (22/7) × 7 × 7 × 15 = 22 × 7 × 15 = 2 310 cm³.
| 2 |
| 4(b) | Curved surface area = 2 × pi × r × h = 2 × (22/7) × 7 × 15 = 660 cm².
| 2 |
| 4(c) | Volume counts how many unit cubes fill the space, so the unit is cubed; surface area counts how many unit squares cover the faces, so the unit is squared.
| 1 |
| Total for Question 4 | 5 |
— End of mark scheme —