PSLE Mathematics Problem Solving 3

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?

Accepted Answer

$70

Answer

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?

Accepted Answer

30,000 cm³

Answer

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?

Accepted Answer

172.5°

Answer

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?

Accepted Answer

2 hours

Answer

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?

Accepted Answer

$12

Answer

For every 4 pens, Ravi pays for 3. 8 pens = 2 groups of 4. He pays for 6 pens: 6 × $2 = $12.

PSLE Practice Test

PSLE Practice Test

PSLE Mathematics Problem Solving 3