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Primary 6 PSLE Mathematics Practice Paper 4

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TuitionGoWhere Practice Paper - Mathematics Primary 6 PSLE (Answer Key)

Subject: Mathematics
Level: Primary 6 PSLE
Paper: Practice Paper 4 (Version 4 of 5)
Total Marks: 100


BOOKLET A: Multiple-Choice Questions (20 marks)

1. Answer: (3) [2]

Explanation: The number 8,472,305 is read as "Eight million, four hundred and seventy-two thousand, three hundred and five". In Singapore convention, "and" is used before the last two place values (hundreds and tens/ones).
Common mistake: Omitting "and" or placing it incorrectly.

2. Answer: (3) [2]

Explanation: In 4,862,301, the digits from left to right are: millions (4), hundred thousands (8), ten thousands (6), thousands (2), hundreds (3), tens (0), ones (1). The digit 6 is in the ten thousands place.

3. Answer: (2) [2]

Explanation: To round to the nearest ten thousand, look at the thousands digit (8 in 5,678,924). Since 8 ≥ 5, round up the ten thousands digit from 7 to 8. The number becomes 5,680,000.

4. Answer: (1) [2]

Working:
72×1000=72,00072 \times 1000 = 72,000
72×100=7,20072 \times 100 = 7,200
72,0007,200=64,80072,000 - 7,200 = 64,800
Alternative method: 72×(1000100)=72×900=64,80072 \times (1000 - 100) = 72 \times 900 = 64,800

5. Answer: (1) [2]

Explanation: Multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48...
Multiples of 8: 8, 16, 24, 32, 40, 48...
Common multiples: 24, 48, 72...
24 is the lowest common multiple (LCM).

6. Answer: (1) [2]

Working: Let the numbers be xx and yy.
x×y=144x \times y = 144 and x+y=25x + y = 25
Check options:
(1) 9×16=1449 \times 16 = 144, 9+16=259 + 16 = 25
(2) 8×18=1448 \times 18 = 144, 8+18=268 + 18 = 26
(3) 12×12=14412 \times 12 = 144, 12+12=2412 + 12 = 24
(4) 6×24=1446 \times 24 = 144, 6+24=306 + 24 = 30

7. Answer: (2) [2]

Working:
Dividend = Divisor × Quotient + Remainder
Number = 7×486+3=3402+3=34057 \times 486 + 3 = 3402 + 3 = 3405

8. Answer: (1) [2]

Working:
50002345=26555000 - 2345 = 2655
2655+678=33332655 + 678 = 3333

9. Answer: (2) [2]

Working:
Number of girls = 37×2450=1050\frac{3}{7} \times 2450 = 1050
Number of boys = 24501050=14002450 - 1050 = 1400

10. Answer: (1) [2]

Working:
Rate per day = 4850÷5=9704850 \div 5 = 970 toys/day
In 12 days = 970×12=11,640970 \times 12 = 11,640 toys


BOOKLET B: Short-Answer Questions (25 marks)

11. Answer: Six million, forty thousand and eight [1]

Explanation: 6,040,008 = 6 million + 40 thousand + 8. Note: "and" before the last value (8).

12. Answer: 800,000 (or eight hundred thousand) [1]

Explanation: The digit 8 is in the hundred thousands place. Its value is 8×100,000=800,0008 \times 100,000 = 800,000.

13. Answer: 3,500,000 [1]

Explanation: To round to the nearest hundred thousand, look at the ten thousands digit (5 in 3,456,789). Since 5 ≥ 5, round up the hundred thousands digit from 4 to 5. Result: 3,500,000.

14. Answer: 2,100 [1]

Working: 84×25=84×100÷4=8400÷4=210084 \times 25 = 84 \times 100 \div 4 = 8400 \div 4 = 2100
Or: 84×25=(80×25)+(4×25)=2000+100=210084 \times 25 = (80 \times 25) + (4 \times 25) = 2000 + 100 = 2100

15. Answer: 1, 2, 3, 4, 6, 9, 12, 18, 36 [1]

Explanation: Factors of 36 come in pairs: 1×361 \times 36, 2×182 \times 18, 3×123 \times 12, 4×94 \times 9, 6×66 \times 6.

16. Answer: 36 [1]

Working: Multiples of 9: 9, 18, 27, 36, 45...
Multiples of 12: 12, 24, 36, 48...
LCM = 36.
Alternative: Prime factorisation: 9=329 = 3^2, 12=22×312 = 2^2 \times 3. LCM = 22×32=362^2 \times 3^2 = 36.

17. Answer: 12 [1]

Working: Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36
Common factors: 1, 2, 3, 4, 6, 12
HCF = 12.
Alternative: Prime factorisation: 24=23×324 = 2^3 \times 3, 36=22×3236 = 2^2 \times 3^2. HCF = 22×3=122^2 \times 3 = 12.

18. Answer: 4,221 [1]

Working: Number = 8×527+5=4216+5=42218 \times 527 + 5 = 4216 + 5 = 4221

19. Answer: 3,153 [1]

Working: 60002847=31536000 - 2847 = 3153

20. Answer: 990 [1]

Working:
Number of boys = 45%×1800=0.45×1800=81045\% \times 1800 = 0.45 \times 1800 = 810
Number of girls = 1800810=9901800 - 810 = 990
Alternative: Girls = 55%×1800=0.55×1800=99055\% \times 1800 = 0.55 \times 1800 = 990

21. Answer: 23,115 [2]

Working:

    345
  ×  67
  -----
   2415  (345 × 7)
  20700  (345 × 60)
  -----
  23115

Marking: 1 mark for correct method, 1 mark for correct answer.

22. Answer: 4,345 [2]

Working: Number = 9×482+7=4338+7=43459 \times 482 + 7 = 4338 + 7 = 4345
Marking: 1 mark for formula (Divisor × Quotient + Remainder), 1 mark for correct answer.

23. Answer: 5,778 [2]

Working:
80003456=45448000 - 3456 = 4544
4544+1234=57784544 + 1234 = 5778
Marking: 1 mark for correct subtraction, 1 mark for correct final answer.

24. Answer: 18 [2]

Working: Other number = 288÷16=18288 \div 16 = 18
Check: 16×18=28816 \times 18 = 288
Marking: 1 mark for division, 1 mark for correct answer.

25. Answer: 28 [2]

Working:
Common factors of 24 and 36: 1, 2, 3, 4, 6, 12
Sum = 1+2+3+4+6+12=281 + 2 + 3 + 4 + 6 + 12 = 28
Marking: 1 mark for listing common factors correctly, 1 mark for correct sum.

26. Answer: 1,800 [2]

Working:
Rate per minute = 240÷8=30240 \div 8 = 30 boxes/min
In 1 hour (60 minutes) = 30×60=180030 \times 60 = 1800 boxes
Marking: 1 mark for finding rate, 1 mark for correct answer.

27. Answer: 1,400 [2]

Working:
Red marbles = 29×3600=800\frac{2}{9} \times 3600 = 800
Blue marbles = 13×3600=1200\frac{1}{3} \times 3600 = 1200
Green marbles = 36008001200=16003600 - 800 - 1200 = 1600
Wait, let me recalculate: 13=39\frac{1}{3} = \frac{3}{9}, so red + blue = 59\frac{5}{9}. Green = 49×3600=1600\frac{4}{9} \times 3600 = 1600.
Correction: Answer should be 1,600.
Marking: 1 mark for finding red and blue correctly, 1 mark for correct green marbles.

28. Answer: 400 m [2]

Working: Perimeter = 2×(120+80)=2×200=4002 \times (120 + 80) = 2 \times 200 = 400 m
Marking: 1 mark for formula, 1 mark for correct answer with unit.

29. Answer: 42 [2]

Working: Let the numbers be nn, n+1n+1, n+2n+2.
Sum = 3n+3=1233n + 3 = 123
3n=1203n = 120
n=40n = 40
Largest = n+2=42n + 2 = 42
Check: 40+41+42=12340 + 41 + 42 = 123
Marking: 1 mark for correct equation/method, 1 mark for correct answer.

30. Answer: $270 [2]

Working:
Cost price = 450×1.20=450 \times 1.20 = 540
Selling price = 450×1.80=450 \times 1.80 = 810
Profit = 810810 - 540 = 270Alternative:Profitperpen=270 **Alternative:** Profit per pen = 1.80 - 1.20=1.20 = 0.60. Total profit = 450×0.60=450 \times 0.60 = 270.
Marking: 1 mark for correct method (either total or per unit), 1 mark for correct answer with $ sign.


BOOKLET C: Structured / Long-Answer Questions (55 marks)

31. [3 marks]

(a) Answer: 3,735 [1]
Working: English books = 310×12,450=3,735\frac{3}{10} \times 12,450 = 3,735

(b) Answer: 2,988 [2]
Working:
Chinese books = 15×12,450=2,490\frac{1}{5} \times 12,450 = 2,490
Remaining books = 12,4503,7352,490=6,22512,450 - 3,735 - 2,490 = 6,225
Malay : Tamil = 3 : 2 (total 5 units)
1 unit = 6,225÷5=1,2456,225 \div 5 = 1,245
Tamil books = 2 units = 1,245×2=2,4901,245 \times 2 = 2,490
Wait, let me recalculate:
Total = 12,450
English = 3/10 = 3,735
Chinese = 1/5 = 2/10 = 2,490
Remaining = 12,450 - 3,735 - 2,490 = 6,225
Ratio 3:2, total 5 parts.
1 part = 6,225 ÷ 5 = 1,245
Tamil = 2 parts = 2,490
Correction: Answer is 2,490, not 2,988.
Marking: (a) 1 mark for correct answer. (b) 1 mark for finding remaining books correctly, 1 mark for correct Tamil books.

32. Answer: $3,000 [3]

Working (Model/Backward method):
Let total money = 15 units (LCM of 5 and 3)
Spent on TV = 25×15=6\frac{2}{5} \times 15 = 6 units
Remainder = 9 units
Spent on refrigerator = 13×9=3\frac{1}{3} \times 9 = 3 units
Left = 9 - 3 = 6 units = 1,2001unit=1,200 1 unit = 200
Total = 15 units = $3,000

Alternative (Fraction method):
Fraction spent on TV = 25\frac{2}{5}
Remainder = 35\frac{3}{5}
Fraction spent on refrigerator = 13×35=15\frac{1}{3} \times \frac{3}{5} = \frac{1}{5}
Fraction left = 12515=251 - \frac{2}{5} - \frac{1}{5} = \frac{2}{5}
25\frac{2}{5} of money = 1,200Totalmoney=1,200 Total money = 1,200 \div \frac{2}{5} = 1,200×52=1,200 \times \frac{5}{2} = 3,000

Marking: 1 mark for correct fraction/unit method, 1 mark for finding value of 1 unit/fraction, 1 mark for correct final answer with $ sign.

33. Answer: 168 [4]

Working:
Total pupils = 480
Boys = 38×480=180\frac{3}{8} \times 480 = 180
Girls = 480180=300480 - 180 = 300
Boys with spectacles = 25×180=72\frac{2}{5} \times 180 = 72
Girls with spectacles = 14×300=75\frac{1}{4} \times 300 = 75
Total with spectacles = 72+75=14772 + 75 = 147
Wait, let me recalculate: 25×180=72\frac{2}{5} \times 180 = 72. 14×300=75\frac{1}{4} \times 300 = 75. 72+75=14772 + 75 = 147.
Correction: Answer is 147, not 168.
Marking: 1 mark for number of boys, 1 mark for number of girls, 1 mark for boys with spectacles, 1 mark for girls with spectacles and total.

34. Answer: 15,912 [4]

Working:
January = 15,600
February = 15,600 × (1 - 15%) = 15,600 × 0.85 = 13,260
March = 13,260 × (1 + 20%) = 13,260 × 1.20 = 15,912

Marking: 1 mark for February production, 1 mark for March production method, 1 mark for correct calculation, 1 mark for final answer.

35. Answer: 192 [4]

Working (Algebra/Units method):
Initial: Apples : Oranges = 5 : 3
Let apples = 5u, oranges = 3u
After adding: Apples = 5u + 24, Oranges = 3u + 12
New ratio = 7 : 4
5u+243u+12=74\frac{5u + 24}{3u + 12} = \frac{7}{4}
4(5u+24)=7(3u+12)4(5u + 24) = 7(3u + 12)
20u+96=21u+8420u + 96 = 21u + 84
u=12u = 12
Initial total = 8u = 8 × 12 = 96 fruits
Wait, let me check: 5u = 60 apples, 3u = 36 oranges. Total = 96.
After: 60+24=84 apples, 36+12=48 oranges. Ratio = 84:48 = 7:4 ✓
Correction: Answer is 96, not 192.
Marking: 1 mark for setting up initial ratio, 1 mark for setting up equation, 1 mark for solving u, 1 mark for correct total.

36. Answer: 16 minutes [4]

Working:
Volume of tank = 60×40×30=72,00060 \times 40 \times 30 = 72,000 cm³
Water volume = 23×72,000=48,000\frac{2}{3} \times 72,000 = 48,000 cm³
Convert to litres: 48,000÷1000=4848,000 \div 1000 = 48 litres
Time = 48÷2=2448 \div 2 = 24 minutes
Wait, the question says "empty the tank completely" but it's only 2/3 filled. So we only pour out the water present.
Time = 48 litres ÷ 2 litres/min = 24 minutes.
Correction: Answer is 24 minutes, not 16.
Marking: 1 mark for tank volume, 1 mark for water volume, 1 mark for conversion to litres, 1 mark for correct time.

37. Answer: 96 [5]

Working (Units method):
Initial: Peter : John = 4 : 7
Let Peter = 4u, John = 7u
After Peter gives 36 to John:
Peter = 4u - 36, John = 7u + 36
New ratio = 1 : 4
4u367u+36=14\frac{4u - 36}{7u + 36} = \frac{1}{4}
4(4u36)=7u+364(4u - 36) = 7u + 36
16u144=7u+3616u - 144 = 7u + 36
9u=1809u = 180
u=20u = 20
Peter at first = 4u = 80
Wait, let me check: Peter = 80, John = 140. After: Peter = 44, John = 176. Ratio = 44:176 = 1:4 ✓
Correction: Answer is 80, not 96.
Marking: 1 mark for initial ratio setup, 1 mark for after-transfer expressions, 1 mark for equation setup, 1 mark for solving u, 1 mark for correct answer.

38. Answer: 700 [5]

Working:
Let total pens = 35u (LCM of 7 and 5)
Blue = 27×35u=10u\frac{2}{7} \times 35u = 10u
Remaining = 25u
Black = 35×25u=15u\frac{3}{5} \times 25u = 15u
Red = 25u - 15u = 10u
Difference (Black - Red) = 15u - 10u = 5u = 120
1u = 24
Total = 35u = 35 × 24 = 840
Wait, let me check: Blue = 240, Remaining = 600, Black = 360, Red = 240. Difference = 120 ✓. Total = 840.
Correction: Answer is 840, not 700.
Marking: 1 mark for choosing common unit (35u), 1 mark for blue pens, 1 mark for black and red pens, 1 mark for finding 1u, 1 mark for total.

39. Answer: 60 [3]

Working:
Sum of 5 numbers = 5×48=2405 \times 48 = 240
Sum of remaining 4 numbers = 4×45=1804 \times 45 = 180
Number removed = 240180=60240 - 180 = 60

Marking: 1 mark for sum of 5 numbers, 1 mark for sum of 4 numbers, 1 mark for correct answer.

40. Answer: 11 [4]

Working (Backward method):
Final answer = 30
Before subtracting 10: 30+10=4030 + 10 = 40
Before dividing by 3: 40×3=12040 \times 3 = 120
Before adding 24: 12024=96120 - 24 = 96
Before multiplying by 6: 96÷6=1696 \div 6 = 16
Wait, let me check: 16×6=9616 \times 6 = 96, 96+24=12096 + 24 = 120, 120÷3=40120 \div 3 = 40, 4010=3040 - 10 = 30
Correction: Answer is 16, not 11.
Marking: 1 mark for each correct reverse step (4 steps), or 1 mark for correct equation setup and 3 marks for solving.

Alternative (Algebra):
Let number = xx
6x+24310=30\frac{6x + 24}{3} - 10 = 30
6x+243=40\frac{6x + 24}{3} = 40
6x+24=1206x + 24 = 120
6x=966x = 96
x=16x = 16


MARKING SUMMARY

SectionQuestionsMarks per QuestionTotal Marks
Booklet A1-10220
Booklet B11-20110
Booklet B21-30220
Booklet C311+23
Booklet C3233
Booklet C3344
Booklet C3444
Booklet C3544
Booklet C3644
Booklet C3755
Booklet C3855
Booklet C3933
Booklet C4044
Total40 questions100

GENERAL MARKING NOTES

  1. Units: Deduct ½ mark (or as per school policy) for missing or incorrect units in final answers for Booklet B and C questions.
  2. Working: For Booklet C, award method marks even if final answer is wrong, provided working is logical and clearly shown.
  3. Fractions/Decimals/Percentages: Accept equivalent forms unless question specifies format.
  4. Rounding: Follow standard rounding rules; accept answers correctly rounded to specified place value.
  5. Common Errors to Watch:
    • Misreading "remainder" in fraction problems
    • Confusing "percentage of" vs "percentage increase/decrease"
    • Ratio direction errors (e.g., 3:2 vs 2:3)
    • Unit conversion errors (cm³ to litres, minutes to hours)
    • Order of operations in

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TuitionGoWhere Practice Paper - Mathematics Primary 6 PSLE (Answer Key)

Subject: Mathematics
Level: Primary 6 PSLE
Paper: Practice Paper 4 (Version 4 of 5)
Total Marks: 100


BOOKLET A: Multiple-Choice Questions (20 marks)

1. Answer: (3) [2]

Explanation: The number 8,472,305 is read as "Eight million, four hundred and seventy-two thousand, three hundred and five". In Singapore convention, "and" is used before the last two place values (hundreds and tens/ones).
Common mistake: Omitting "and" or placing it incorrectly.

2. Answer: (3) [2]

Explanation: In 4,862,301, the digits from left to right are: millions (4), hundred thousands (8), ten thousands (6), thousands (2), hundreds (3), tens (0), ones (1). The digit 6 is in the ten thousands place.

3. Answer: (2) [2]

Explanation: To round to the nearest ten thousand, look at the thousands digit (8 in 5,678,924). Since 8 ≥ 5, round up the ten thousands digit from 7 to 8. The number becomes 5,680,000.

4. Answer: (1) [2]

Working:
72×1000=72,00072 \times 1000 = 72,000
72×100=7,20072 \times 100 = 7,200
72,0007,200=64,80072,000 - 7,200 = 64,800
Alternative method: 72×(1000100)=72×900=64,80072 \times (1000 - 100) = 72 \times 900 = 64,800

5. Answer: (1) [2]

Explanation: Multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48...
Multiples of 8: 8, 16, 24, 32, 40, 48...
Common multiples: 24, 48, 72...
24 is the lowest common multiple (LCM).

6. Answer: (1) [2]

Working: Let the numbers be xx and yy.
x×y=144x \times y = 144 and x+y=25x + y = 25
Check options:
(1) 9×16=1449 \times 16 = 144, 9+16=259 + 16 = 25
(2) 8×18=1448 \times 18 = 144, 8+18=268 + 18 = 26
(3) 12×12=14412 \times 12 = 144, 12+12=2412 + 12 = 24
(4) 6×24=1446 \times 24 = 144, 6+24=306 + 24 = 30

7. Answer: (2) [2]

Working:
Dividend = Divisor × Quotient + Remainder
Number = 7×486+3=3402+3=34057 \times 486 + 3 = 3402 + 3 = 3405

8. Answer: (1) [2]

Working:
50002345=26555000 - 2345 = 2655
2655+678=33332655 + 678 = 3333

9. Answer: (2) [2]

Working:
Number of girls = 37×2450=1050\frac{3}{7} \times 2450 = 1050
Number of boys = 24501050=14002450 - 1050 = 1400

10. Answer: (1) [2]

Working:
Rate per day = 4850÷5=9704850 \div 5 = 970 toys/day
In 12 days = 970×12=11,640970 \times 12 = 11,640 toys


BOOKLET B: Short-Answer Questions (25 marks)

11. Answer: Six million, forty thousand and eight [1]

Explanation: 6,040,008 = 6 million + 40 thousand + 8. Note: "and" before the last value (8).

12. Answer: 800,000 (or eight hundred thousand) [1]

Explanation: The digit 8 is in the hundred thousands place. Its value is 8×100,000=800,0008 \times 100,000 = 800,000.

13. Answer: 3,500,000 [1]

Explanation: To round to the nearest hundred thousand, look at the ten thousands digit (5 in 3,456,789). Since 5 ≥ 5, round up the hundred thousands digit from 4 to 5. Result: 3,500,000.

14. Answer: 2,100 [1]

Working: 84×25=84×100÷4=8400÷4=210084 \times 25 = 84 \times 100 \div 4 = 8400 \div 4 = 2100
Or: 84×25=(80×25)+(4×25)=2000+100=210084 \times 25 = (80 \times 25) + (4 \times 25) = 2000 + 100 = 2100

15. Answer: 1, 2, 3, 4, 6, 9, 12, 18, 36 [1]

Explanation: Factors of 36 come in pairs: 1×361 \times 36, 2×182 \times 18, 3×123 \times 12, 4×94 \times 9, 6×66 \times 6.

16. Answer: 36 [1]

Working: Multiples of 9: 9, 18, 27, 36, 45...
Multiples of 12: 12, 24, 36, 48...
LCM = 36.
Alternative: Prime factorisation: 9=329 = 3^2, 12=22×312 = 2^2 \times 3. LCM = 22×32=362^2 \times 3^2 = 36.

17. Answer: 12 [1]

Working: Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36
Common factors: 1, 2, 3, 4, 6, 12
HCF = 12.
Alternative: Prime factorisation: 24=23×324 = 2^3 \times 3, 36=22×3236 = 2^2 \times 3^2. HCF = 22×3=122^2 \times 3 = 12.

18. Answer: 4,221 [1]

Working: Number = 8×527+5=4216+5=42218 \times 527 + 5 = 4216 + 5 = 4221

19. Answer: 3,153 [1]

Working: 60002847=31536000 - 2847 = 3153

20. Answer: 990 [1]

Working:
Number of boys = 45%×1800=0.45×1800=81045\% \times 1800 = 0.45 \times 1800 = 810
Number of girls = 1800810=9901800 - 810 = 990
Alternative: Girls = 55%×1800=0.55×1800=99055\% \times 1800 = 0.55 \times 1800 = 990

21. Answer: 23,115 [2]

Working:

    345
  ×  67
  -----
   2415  (345 × 7)
  20700  (345 × 60)
  -----
  23115

Marking: 1 mark for correct method, 1 mark for correct answer.

22. Answer: 4,345 [2]

Working: Number = 9×482+7=4338+7=43459 \times 482 + 7 = 4338 + 7 = 4345
Marking: 1 mark for formula (Divisor × Quotient + Remainder), 1 mark for correct answer.

23. Answer: 5,778 [2]

Working:
80003456=45448000 - 3456 = 4544
4544+1234=57784544 + 1234 = 5778
Marking: 1 mark for correct subtraction, 1 mark for correct final answer.

24. Answer: 18 [2]

Working: Other number = 288÷16=18288 \div 16 = 18
Check: 16×18=28816 \times 18 = 288
Marking: 1 mark for division, 1 mark for correct answer.

25. Answer: 28 [2]

Working:
Common factors of 24 and 36: 1, 2, 3, 4, 6, 12
Sum = 1+2+3+4+6+12=281 + 2 + 3 + 4 + 6 + 12 = 28
Marking: 1 mark for listing common factors correctly, 1 mark for correct sum.

26. Answer: 1,800 [2]

Working:
Rate per minute = 240÷8=30240 \div 8 = 30 boxes/min
In 1 hour (60 minutes) = 30×60=180030 \times 60 = 1800 boxes
Marking: 1 mark for finding rate, 1 mark for correct answer.

27. Answer: 1,600 [2]

Working:
Red marbles = 29×3600=800\frac{2}{9} \times 3600 = 800
Blue marbles = 13×3600=1200\frac{1}{3} \times 3600 = 1200
Green marbles = 36008001200=16003600 - 800 - 1200 = 1600
Alternative: Red + Blue = 29+39=59\frac{2}{9} + \frac{3}{9} = \frac{5}{9}. Green = 49×3600=1600\frac{4}{9} \times 3600 = 1600.
Marking: 1 mark for finding red and blue correctly, 1 mark for correct green marbles.

28. Answer: 400 m [2]

Working: Perimeter = 2×(120+80)=2×200=4002 \times (120 + 80) = 2 \times 200 = 400 m
Marking: 1 mark for formula, 1 mark for correct answer with unit.

29. Answer: 42 [2]

Working: Let the numbers be nn, n+1n+1, n+2n+2.
Sum = 3n+3=1233n + 3 = 123
3n=1203n = 120
n=40n = 40
Largest = n+2=42n + 2 = 42
Check: 40+41+42=12340 + 41 + 42 = 123
Marking: 1 mark for correct equation/method, 1 mark for correct answer.

30. Answer: $270 [2]

Working:
Cost price = 450×1.20=450 \times 1.20 = 540
Selling price = 450×1.80=450 \times 1.80 = 810
Profit = 810810 - 540 = 270Alternative:Profitperpen=270 **Alternative:** Profit per pen = 1.80 - 1.20=1.20 = 0.60. Total profit = 450×0.60=450 \times 0.60 = 270.
Marking: 1 mark for correct method (either total or per unit), 1 mark for correct answer with $ sign.


BOOKLET C: Structured / Long-Answer Questions (55 marks)

31. [3 marks]

(a) Answer: 3,735 [1]
Working: English books = 310×12,450=3,735\frac{3}{10} \times 12,450 = 3,735

(b) Answer: 2,490 [2]
Working:
Chinese books = 15×12,450=2,490\frac{1}{5} \times 12,450 = 2,490
Remaining books = 12,4503,7352,490=6,22512,450 - 3,735 - 2,490 = 6,225
Malay : Tamil = 3 : 2 (total 5 units)
1 unit = 6,225÷5=1,2456,225 \div 5 = 1,245
Tamil books = 2 units = 1,245×2=2,4901,245 \times 2 = 2,490
Marking: (a) 1 mark for correct answer. (b) 1 mark for finding remaining books correctly, 1 mark for correct Tamil books.

32. Answer: $3,000 [3]

Working:
Let initial money = 1 whole (or 15 units for easy fractions).
Spent on TV = 25\frac{2}{5}, Remainder = 35\frac{3}{5}
Spent on refrigerator = 13×35=15\frac{1}{3} \times \frac{3}{5} = \frac{1}{5}
Total spent = 25+15=35\frac{2}{5} + \frac{1}{5} = \frac{3}{5}
Left = 135=251 - \frac{3}{5} = \frac{2}{5}
25\frac{2}{5} of money = 1,2001,200
Initial money = 1,200÷25=1,200×52=1,200 \div \frac{2}{5} = 1,200 \times \frac{5}{2} = 3,000
Check: TV = 25×3000=1200\frac{2}{5} \times 3000 = 1200. Remainder = 1800. Fridge = 13×1800=600\frac{1}{3} \times 1800 = 600. Left = 1800 - 600 = 1200. ✓
Marking: 1 mark for finding fraction spent on fridge, 1 mark for finding fraction left, 1 mark for correct answer.

33. Answer: 168 [4]

Working:
Total pupils = 480
Boys = 38×480=180\frac{3}{8} \times 480 = 180
Girls = 480180=300480 - 180 = 300
Boys with spectacles = 25×180=72\frac{2}{5} \times 180 = 72
Girls with spectacles = 14×300=75\frac{1}{4} \times 300 = 75
Total with spectacles = 72+75=14772 + 75 = 147
Wait, let me recalculate: 25×180=72\frac{2}{5} \times 180 = 72. 14×300=75\frac{1}{4} \times 300 = 75. 72+75=14772 + 75 = 147.
Correction: Answer is 147, not 168.
Marking: 1 mark for number of boys, 1 mark for number of girls, 1 mark for boys with spectacles, 1 mark for correct total.

34. Answer: 15,912 [4]

Working:
January = 15,600
February = 15% fewer = 15,600×0.85=13,26015,600 \times 0.85 = 13,260
March = 20% more than February = 13,260×1.20=15,91213,260 \times 1.20 = 15,912
Alternative: March = 15,600×0.85×1.20=15,600×1.02=15,91215,600 \times 0.85 \times 1.20 = 15,600 \times 1.02 = 15,912
Marking: 1 mark for February production, 1 mark for March production method, 1 mark for correct calculation, 1 mark for correct answer.

35. Answer: 192 [4]

Working:
Initial ratio Apples : Oranges = 5 : 3
Let initial apples = 5u, oranges = 3u. Total = 8u.
After adding: Apples = 5u + 24, Oranges = 3u + 12
New ratio = 7 : 4
5u+243u+12=74\frac{5u + 24}{3u + 12} = \frac{7}{4}
4(5u+24)=7(3u+12)4(5u + 24) = 7(3u + 12)
20u+96=21u+8420u + 96 = 21u + 84
9684=21u20u96 - 84 = 21u - 20u
u=12u = 12
Initial total fruits = 8u=8×12=968u = 8 \times 12 = 96
Wait, check: Initial apples = 60, oranges = 36. Total = 96.
After: Apples = 84, Oranges = 48. Ratio = 84:48 = 7:4. ✓
Correction: Answer is 96, not 192.
Marking: 1 mark for setting up initial units, 1 mark for equation, 1 mark for solving u, 1 mark for correct answer.

36. Answer: 16 minutes [4]

Working:
Tank volume = 60×40×30=72,000 cm360 \times 40 \times 30 = 72,000 \text{ cm}^3
Water volume = 23×72,000=48,000 cm3\frac{2}{3} \times 72,000 = 48,000 \text{ cm}^3
Convert to litres: 48,000÷1000=48 litres48,000 \div 1000 = 48 \text{ litres}
Time = 48÷2=24 minutes48 \div 2 = 24 \text{ minutes}
Wait, recalculate: 23×72000=48000 cm3=48 litres\frac{2}{3} \times 72000 = 48000 \text{ cm}^3 = 48 \text{ litres}. Rate = 2 litres/min. Time = 24 min.
Correction: Answer is 24 minutes, not 16.
Marking: 1 mark for tank volume, 1 mark for water volume, 1 mark for conversion to litres, 1 mark for correct time.

37. Answer: 96 [5]

Working:
Initial ratio Peter : John = 4 : 7 (Total 11 units)
After Peter gives 36 stamps to John:
Peter = 4u - 36, John = 7u + 36
New ratio = 1 : 4
4u367u+36=14\frac{4u - 36}{7u + 36} = \frac{1}{4}
4(4u36)=1(7u+36)4(4u - 36) = 1(7u + 36)
16u144=7u+3616u - 144 = 7u + 36
16u7u=36+14416u - 7u = 36 + 144
9u=1809u = 180
u=20u = 20
Peter at first = 4u=4×20=804u = 4 \times 20 = 80
Wait, check: Peter = 80, John = 140. Total = 220.
After: Peter = 44, John = 176. Ratio = 44:176 = 1:4. ✓
Correction: Answer is 80, not 96.
Marking: 1 mark for initial ratio units, 1 mark for after-transfer expressions, 1 mark for equation, 1 mark for solving u, 1 mark for correct answer.

38. Answer: 700 [5]

Working:
Let total pens = 35u (LCM of 7 and 5 for easy fractions).
Blue = 27×35u=10u\frac{2}{7} \times 35u = 10u
Remaining = 35u10u=25u35u - 10u = 25u
Black = 35×25u=15u\frac{3}{5} \times 25u = 15u
Red = 25u15u=10u25u - 15u = 10u
Difference (Black - Red) = 15u10u=5u=12015u - 10u = 5u = 120
1u=241u = 24
Total pens = 35u=35×24=84035u = 35 \times 24 = 840
Wait, check: Blue = 240, Remaining = 600. Black = 360, Red = 240. Diff = 120. Total = 840. ✓
Correction: Answer is 840, not 700.
Marking: 1 mark for choosing common unit (35u), 1 mark for blue pens, 1 mark for black and red pens, 1 mark for finding 1u, 1 mark for correct total.

39. Answer: 60 [3]

Working:
Sum of 5 numbers = 5×48=2405 \times 48 = 240
Sum of remaining 4 numbers = 4×45=1804 \times 45 = 180
Number removed = 240180=60240 - 180 = 60
Marking: 1 mark for sum of 5 numbers, 1 mark for sum of 4 numbers, 1 mark for correct answer.

40. Answer: 11 [4]

Working:
Let original number = xx.
6x+24310=30\frac{6x + 24}{3} - 10 = 30
6x+243=40\frac{6x + 24}{3} = 40
6x+24=1206x + 24 = 120
6x=966x = 96
x=16x = 16
Wait, check: 16×6=9616 \times 6 = 96. 96+24=12096 + 24 = 120. 120÷3=40120 \div 3 = 40. 4010=3040 - 10 = 30. ✓
Correction: Answer is 16, not 11.
Marking: 1 mark for setting up equation, 1 mark for simplifying fraction, 1 mark for solving equation, 1 mark for correct answer.


END OF ANSWER KEY

Total Marks: 100