Chapter 6 Practice Paper: Percentage — mark scheme
Secondary 1 · Lower Secondary Mathematics (G2 / G3)
Mark scheme
Percentage
Chapter 6 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 | C30% means 30/100, and 90 × 30/100 = 27. | 1 |
| 2 | B7/20 = 35/100 = 35%. Multiply the fraction by 100%. | 1 |
| 3 | A45% of the number is 18, so the number is 18 ÷ 0.45 = 40. | 1 |
| 4 | DThe increase is 8/100 × 65 = $5.20, so the new price is 65 + 5.20 = $70.20. | 1 |
| 5 | BThe discount is 20% of 95 = $19, so the shirt costs 95 - 19 = $76. (Careful: $76 is the price, not the discount.) | 1 |
| 6 | CThe $109 is 109% of the pre-GST price, so the pre-GST price is 109 ÷ 1.09 = $100. Taking 9% of 109 is the classic trap. | 1 |
| 7 | AThe change is 12, and it is compared with the original: 12/50 × 100% = 24% increase. | 1 |
| 8 | DEach year earns 3% of 800 = $24, so 2 years earn $48. The option $848 would be the total amount, not the interest. | 1 |
| 9 | CConvert: 4/9 = 0.4444... , 47% = 0.47. Comparing 0.45, 0.4444..., 0.47 and 0.444: the smallest is 0.444. | 1 |
| 10 | BThe new salary is 125% of the original, so the original is 2 400 ÷ 1.25 = $1 920. Check: 1 920 × 1.25 = 2 400. | 1 |
Section B: Structured questions[20 marks]
| Question | Answer and marking points | Marks |
|---|---|---|
| 1(a) | 3/5 × 100% = 60% [1] | 1 |
| 1(b) | 75 × 24/100 = 18
| 2 |
| 1(c) | (4.50 ÷ 18) × 100% = 25%
The dollar units cancel; award the method mark even if the division slips. | 2 |
| Total for Question 1 | 5 | |
| 2(a) | The increase is 15/100 × 240 = 36, so the new value is 276.
| 2 |
| 2(b) | The decrease is 30/100 × 90 = 27, so the new value is 63.
| 2 |
| 2(c) | Change = 17, and 17/85 × 100% = 20% increase. [1] | 1 |
| Total for Question 2 | 5 | |
| 3(a) | The sale price is 80% of the original, so the original is 96 ÷ 0.80 = $120.
Do not accept $115.20 from adding 20% of 96 — the percentage must refer to the original. | 3 |
| 3(b) | The new value is 125% of the number, so the number is 75 ÷ 1.25 = 60.
| 2 |
| Total for Question 3 | 5 | |
| 4(a) | GST = 9/100 × 80 = $7.20, so the total is 80 + 7.20 = $87.20.
| 2 |
| 4(b) | Interest per year = 2.5/100 × 1 200 = $30, so 3 years earn 3 × 30 = $90.
| 2 |
| 4(c) | 1 200 + 90 = $1 290 [1] The amount includes the original principal; $90 alone is the interest, not the amount. | 1 |
| Total for Question 4 | 5 |
— End of mark scheme —