What is the least number of straight lines needed to draw the figure given below?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 9
Each full straight line counts once, however many pieces other lines cut it into. In the figure below every line is numbered; group them by direction.
Horizontal lines (2): 1, 2
Vertical lines (2): 3, 4
Slanting lines (5): 5, 6, 7, 8, 9
Total \(=2+2+5=9\) straight lines.
Why the other options are incorrect
Option (1) 17 — Incorrect. This counts every piece between two corners or crossings as a separate line.
Option (2) 7 — Incorrect. This leaves out the 2 vertical lines.
Option (4) 4 — Incorrect. This leaves out the 5 slanting lines.