Problem 19 · 2022 Math Kangaroo
Stretch
Spatial & Visual Reasoning
path-tracingcube-views
A pyramid is built from cubes (see diagram), and every cube has side length 10 cm. An ant crawls along the line drawn across the pyramid (see diagram). How long is the path the ant takes?
Show answer
Answer: E — 90 cm
Show hints
Hint 1 of 3
The drawn line is made of short straight pieces, and each piece is exactly one cube-edge long.
Still stuck? Show hint 2 →
Hint 2 of 3
One cube edge is 10 cm, so you only need to count how many cube-edges the whole line covers.
Still stuck? Show hint 3 →
Hint 3 of 3
Trace the line up the steps and back down, counting one edge at a time.
Show solution
Approach: count the cube-edges the line covers, each 10 cm
- The ant's line follows the steps of the pyramid, and every little piece is one cube-edge of 10 cm.
- Tracing the line up over the steps and down the other side, it covers 9 cube-edges.
- So the path is 9 × 10 cm = 90 cm — answer E.
Mark:
· log in to save