Bricks in a wall — Mensuration Aptitude Question
Bricks in a wall: How many bricks measuring 25 cm × 10 cm × 8 cm are needed to build a wall 5 m × 3 m × 16 cm? Answer and worked solution on CodeKairo.
- Topic: Mensuration
- Section: Quantitative Aptitude
- Difficulty: Hard
- Time target: 105 seconds
Question
How many bricks measuring 25 cm × 10 cm × 8 cm are needed to build a wall 5 m × 3 m × 16 cm?
Options
- 1,000
- 1,200
- 1,500
- 2,000
Show the answer and the worked solution
Correct answer: B. 1,200
Worked solution
- Wall = 500 × 300 × 16 = 24,00,000 cm³.
- Brick = 25 × 10 × 8 = 2,000 cm³.
- Bricks needed = 24,00,000 ÷ 2,000 = 1,200.
Answer: 1,200.
The idea
Convert to a single unit before dividing volumes. Mixing metres and centimetres is the only real difficulty here.
Shortcut. Divide dimension by dimension: 500/25 × 300/10 × 16/8 = 20 × 30 × 2 = 1,200.
Common trap. "2,000" — the brick's volume is 2,000 cm³, and a hurried solver picks that figure from the working instead of dividing it into the wall's 24,00,000 cm³.