Two soft toys are similar. One toy is three times the height of the other.

How much more material is required to make it?

Similarity:Volume and surface area of similar solids

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Since the toys are similar the bigger toy does not only have 3 times greater height but also 3 times greater depth and width (if the toys are 3-dimensional). So the **volume** of bigger toy is **3*3*3=27 times greater**. If the toys are 2-dimensional you will get that bigger toy has **3*3=9 times greater surface area**.

In mathematics this is called homothetic transformation and ratio k which is in your case k=3. So for similar 2-dimensional objects with ratio k ratio of their surface area is `k^2` and for 3-dimensional objects ratio of their volumes is `k^3.`

For further explenation see e.g. *Bruce E. Meserve: Fundamental Concepts of Geometry* or one of the links below.

**Sources:**

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