Maths Olympiad Prep

Track / Stage 4 / 112 of 340 #372 of 1964

Problem 372

AMC 12 late, AIME early
Combinatorics Difficulty 4.8 Multiple choice

In the diagram, how many 1×11 \times 1 squares are shaded in the 8×88 \times 8 grid?

Pick one

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Official solution

In the diagram, there are 7 rows in which there are shaded squares, and there are 7 shaded squares in each row.

Thus, there are 77=497 \cdot 7=49 shaded squares.

ANswer: (E)

Source: NuminaMath-1.5, licensed Apache-2.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.