2002 · Q46
What is the maximum number of pieces 1 cm in diameter and 20 cm long that can be cut out of a cylindrical wooden block 20 cm in length and 3 cm in diameter?
General Mental Ability, Quantitative Aptitude and StatisticsNumber system and arithmetic
- A4
- B5
- C6
- D7
Explanation
In the 3-cm-diameter cross-section, one 1-cm circle fits at the centre and six more pack around it — their centres sit 1 cm from the middle, each touching the centre circle and the wall (1 + 0.5 = 1.5 cm = block radius). Each of these 7 columns runs the full 20-cm length, giving 7 pieces. An eighth 1-cm circle cannot fit in the remaining gaps. Hence (D) is correct.