🦘 Math Kangaroo Grade All Felix 1-2 Ecolier 3-4 Benjamin 5-6 Kadett 7-8 Junior 9-10 Student 11-12 ⇄ switch contest
2010 Math Kangaroo

Problem 3

Problem 3 · 2010 Math Kangaroo Medium
Geometry & Measurement areaspatial-reasoning

The hollow spaces of two empty containers are cubic and have a base area of 1 dm² and 4 dm² respectively. The big container is to be filled with water, using the small one as a scoop. How many full scoops are necessary to fill the big cube?

Show answer
Answer: D — 8
Show hints
Hint 1 of 2
Both hollows are cubes, so a base area also fixes the height.
Still stuck? Show hint 2 →
Hint 2 of 2
Compare the two volumes, not the base areas.
Show solution
Approach: turn base areas into side lengths, then volumes
  1. A cube with base 1 dm² has side 1 dm, so volume 1 dm³.
  2. A cube with base 4 dm² has side 2 dm, so volume 2³ = 8 dm³.
  3. Filling 8 dm³ one scoop (1 dm³) at a time needs 8 scoops.
Mark: · log in to save