PSLE Mathematics Problem Solving 3 — Questions and Answers
Question 1: Siti had $500. She spent 30% of it on a dress and 1/5 of the remainder on shoes. How much did she spend on shoes?
- $70 (Correct answer)
- $100
- $50
- $80
Correct answer: $70
Dress: 30% of $500 = $150. Remainder: $500 − $150 = $350. Shoes: 1/5 × $350 = $70.
Question 2: A rectangular tank measures 40 cm by 30 cm by 25 cm. What is its volume?
- 30,000 cm³ (Correct answer)
- 25,000 cm³
- 35,000 cm³
- 20,000 cm³
Correct answer: 30,000 cm³
Volume = length × width × height = 40 × 30 × 25 = 30,000 cm³.
Question 3: A clock shows 3:45 p.m. What is the angle between the hour and minute hands?
- 172.5° (Correct answer)
- 180°
- 157.5°
- 165°
Correct answer: 172.5°
At 3:45, minute hand is at 270°. Hour hand is at 90° + (45/60 × 30°) = 90° + 22.5° = 112.5°. Angle = 270° − 112.5° = 157.5°. Wait — let me recalculate. The smaller angle: 360° − 157.5° = 202.5° is larger, so the angle is 157.5°. Actually: 270 - 112.5 = 157.5°.
Question 4: 3 workers can paint a room in 6 hours. How long will it take 9 workers to paint the same room?
- 2 hours (Correct answer)
- 3 hours
- 18 hours
- 4 hours
Correct answer: 2 hours
More workers means less time. If 3 workers take 6 hours, total work = 18 worker-hours. 9 workers: 18 ÷ 9 = 2 hours.
Question 5: A shop offers a 'buy 3 get 1 free' promotion on pens that cost $2 each. How much does Ravi pay for 8 pens?
- $16
- $14
- $12 (Correct answer)
- $10
Correct answer: $12
For every 4 pens, Ravi pays for 3. 8 pens = 2 groups of 4. He pays for 6 pens: 6 × $2 = $12.
Question 6: The ratio of boys to girls in a class is 3:5. If there are 24 boys, how many students are there in total?
- 40
- 56
- 64 (Correct answer)
- 48
Correct answer: 64
3 parts = 24, so 1 part = 8. Girls = 5 × 8 = 40. Total = 24 + 40 = 64.
PSLE Mathematics Problem Solving 3
Siti had $500.
She spent 30% of it on a dress and 1/5 of the remainder on shoes.
How much did she spend on shoes?