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UKMT Junior Kangaroo, 2018

Geometry Difficulty 2.0 Junior Find the answer United Kingdom

The two diagrams show a side view and a plan view of a tower made with light and dark coloured blocks. In the tower, only dark coloured blocks are placed on top of dark coloured blocks and only light coloured blocks are placed on top of light coloured blocks. How many blocks in the tower are light coloured?

(A) $9$ (B) $13$ (C) $18$ (D) $20$ (E) $24$

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