Primary 6 PSLE Mathematics Fractions Quiz

Primary 6 PSLE Mathematics Quiz - Fractions - Answer Key

Total Marks: 50 Teaching notes are included so a student new to the topic can follow the concept, method, and reasoning for every answer.

Answer 1. [1 mark]

$\frac{3}{8} + \frac{1}{4}$

• Step 1: Rename $\frac{1}{4}$ as eighths: $\frac{1}{4} = \frac{2}{8}$ (multiply numerator and denominator by 2).
• Step 2: Add numerators: $\frac{3}{8} + \frac{2

<stage5_quiz_answers_md>

Primary 6 PSLE Mathematics Quiz - Fractions - Answer Key

Total Marks: 50 Teaching notes are included so a student new to the topic can follow the concept, method, and reasoning for every answer.

Answer 1. [1 mark]

$\frac{3}{8} + \frac{1}{4}$

• Rename $\frac{1}{4}$ as eighths: $\frac{1}{4} = \frac{2}{8}$.
• Add: $\frac{3}{8} + \frac{2}{8} = \frac{5}{8}$.

Answer: $\frac{5}{8}$

Answer 2. [1 mark]

$\frac{5}{6} - \frac{1}{3}$

• Rename $\frac{1}{3}$ as sixths: $\frac{1}{3} = \frac{2}{6}$.
• Subtract: $\frac{5}{6} - \frac{2}{6} = \frac{3}{6} = \frac{1}{2}$.

Answer: $\frac{1}{2}$

Answer 3. [1 mark]

$\frac{3}{7} \times \frac{14}{9}$

• Multiply numerators and denominators: $\frac{3 \times 14}{7 \times 9} = \frac{42}{63}$.
• Simplify by 21: $\frac{42}{63} = \frac{2}{3}$.

Answer: $\frac{2}{3}$

Answer 4. [1 mark]

$\frac{4}{5} \div 8$

• Dividing by 8 means multiplying by $\frac{1}{8}$: $\frac{4}{5} \times \frac{1}{8} = \frac{4}{40}$.
• Simplify: $\frac{1}{10}$.

Answer: $\frac{1}{10}$

Answer 5. [1 mark]

$6 \div \frac{3}{4}$

• Multiply by the reciprocal: $6 \times \frac{4}{3} = \frac{24}{3} = 8$.

Answer: $8$

Answer 6. [2 marks]

$\frac{2}{3} \div \frac{5}{6}$

• Multiply by the reciprocal: $\frac{2}{3} \times \frac{6}{5} = \frac{12}{15}$.
• Simplify by 3: $\frac{4}{5}$.

Answer: $\frac{4}{5}$

Answer 7. [2 marks]

$\frac{7}{8} \times \frac{4}{21} \div \frac{2}{3}$

• Step 1: $\frac{7}{8} \times \frac{4}{21} = \frac{28}{168} = \frac{1}{6}$.
• Step 2: $\frac{1}{6} \div \frac{2}{3} = \frac{1}{6} \times \frac{3}{2} = \frac{3}{12} = \frac{1}{4}$.

Answer: $\frac{1}{4}$

Answer 8. [2 marks]

$\frac{5}{6} + \frac{7}{9}$

• LCM of 6 and 9 is 18: $\frac{15}{18} + \frac{14}{18} = \frac{29}{18}$.
• As a mixed number: $1\frac{11}{18}$.

Answer: $1\frac{11}{18}$

Answer 9. [2 marks]

Ribbon $\frac{9}{10}$ m cut into pieces of $\frac{3}{20}$ m.

• Number of pieces: $\frac{9}{10} \div \frac{3}{20} = \frac{9}{10} \times \frac{20}{3} = \frac{180}{30} = 6$.

Answer: 6 pieces

Answer 10. [2 marks]

$\left(\frac{3}{4} + \frac{5}{6}\right) \div \frac{7}{12}$

• Step 1 (brackets first): $\frac{9}{12} + \frac{10}{12} = \frac{19}{12}$.
• Step 2: $\frac{19}{12} \times \frac{12}{7} = \frac{19}{7} = 2\frac{5}{7}$.

Answer: $2\frac{5}{7}$

Answer 11. [3 marks]

Mei Ling's beads.

• Bracelet: $84 \times \frac{3}{7} = 36$ beads used. Remaining: $84 - 36 = 48$.
• Necklace: $\frac{1}{4}$ of $48 = 12$ beads used.
• Left: $48 - 12 = 36$.

Answer: 36 beads

Answer 12. [3 marks]

Rope $3\frac{2}{5}$ m $= \frac{17}{5}$ m, pieces of $\frac{3}{8}$ m.

• (a) $\frac{17}{5} \div \frac{3}{8} = \frac{17}{5} \times \frac{8}{3} = \frac{136}{15} = 9\frac{1}{15}$, so 9 whole pieces.
• (b) Length used: $9 \times \frac{3}{8} = \frac{27}{8}$ m. Leftover: $\frac{17}{5} - \frac{27}{8} = \frac{136}{40} - \frac{135}{40} = \frac{1}{40}$ m.

Answer (a): 9 pieces Answer (b): $\frac{1}{40}$ m

Answer 13. [3 marks]

Aisha's book.

• (a) Read: $\frac{2}{5} + \frac{3}{8} = \frac{16}{40} + \frac{15}{40} = \frac{31}{40}$. Unread: $1 - \frac{31}{40} = \frac{9}{40}$.
• (b) Pages left: $240 \times \frac{9}{40} = 54$.

Answer (a): $\frac{9}{40}$ Answer (b): 54 pages

Answer 14. [3 marks]

Rice packed into bags.

• Number of bags: $6 \div \frac{2}{3} = 6 \times \frac{3}{2} = 9$ bags.
• Money collected: 9 \times \4 = $36$.

Answer: $36

Answer 15. [3 marks]

Raju's money.

• After wallet: $\frac{3}{4}$ left. Shirt: $\frac{2}{5} \times \frac{3}{4} = \frac{3}{10}$ spent.
• Fraction left: $\frac{3}{4} - \frac{3}{10} = \frac{15}{20} - \frac{6}{20} = \frac{9}{20}$.
• $\frac{9}{20}$ of money = \54$, so 1 part$= $6$, and 20 parts$= $120$.
• Check: $120 \to$ wallet $30 \to 90 \to$ shirt $36 \to 54$ left. ✓

Answer: $120

Answer 16. [4 marks]

Kai Wen and Priya.

• Kai Wen left with: $\frac{4}{5} \times \frac{1}{2} = \frac{2}{5}$ of his money. Priya left with $\frac{1}{2}$ of hers.
• Equal amounts left: $\frac{2}{5}K = \frac{1}{2}P$, so $P = \frac{4}{5}K$.
• $K + \frac{4}{5}K = 900 \Rightarrow \frac{9}{5}K = 900 \Rightarrow K = 500$.
• Check: KW $500 \to 400 \to 200$ left; Priya $400 \to 200$ left. ✓

Answer: $500

Answer 17. [4 marks]

Mrs Goh's salary.

• Remainder after groceries: $\frac{5}{8}$ of salary. Saved: $\frac{1}{6}$ of remainder $= \frac{5}{8} \times \frac{1}{6} = \frac{5}{48}$ of salary.
• $\frac{5}{48}$ of salary = \450$, so$\frac{1}{48} = $90$.
• Salary = 48 \times \90 = $4320$.
• Check: groceries $1620 \to$ remainder $2700 \to$ holiday $2250 \to$ saved $450$. ✓

Answer: $4320

Answer 18. [4 marks]

Choir members.

• Girls unchanged: $\frac{3}{5} = \frac{12}{20}$ before, $\frac{4}{7} = \frac{12}{21}$ after. Use 12 units for girls.
• Before: 12 girls-units + 8 boys-units = 20 units. After: 12 girls-units + 9 boys-units = 21 units.
• The extra boy-unit = 6 boys joined, so 1 unit = 6.
• Members now: $21 \times 6 = 126$.
• Check: 72 girls, 54 boys; $\frac{72}{126} = \frac{4}{7}$. ✓

Answer: 126 members

Answer 19. [4 marks]

Water tank, day by day (halve, then add 80 ml).

• End of Day 1: $800 \div 2 + 80 = 400 + 80 = 480$ ml.
• End of Day 2: $480 \div 2 + 80 = 240 + 80 = 320$ ml.
• End of Day 3: $320 \div 2 + 80 = 160 + 80 = 240$ ml.

Answer: 240 ml

Answer 20. [4 marks]

Ravi and Sean.

• Both end with the same amount, so Sean spent $90 more than Ravi: Sean$-$Ravi$= 130 - 40 = $90$.
• Ravi $= \frac{5}{6}$ Sean, so the difference is $\frac{1}{6}$ of Sean's money: $\frac{1}{6}S = 90 \Rightarrow S = 540$.
• Ravi $= \frac{5}{6} \times 540 = 450$.
• Check: $450 - 40 = 410$; $540 - 130 = 410$. ✓

Answer: $450

END OF ANSWER KEY