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UKMT Intermediate Mathematical Challenge, 2020

Combinatorics Difficulty 1.0 Junior Find the answer United Kingdom

Kartik wants to shade three of the squares in this grid blue and Lucy wants to shade the remaining two squares red. There are ten possible finished grids. In how many of the finished grids are Lucy's red squares next to each other?

(A) $3$ (B) $4$ (C) $5$ (D) $6$ (E) $8$

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