2020 AMC 8

Complete problem set with solutions and individual problem pages

Problem 25 Hard

Rectangles R_1 and R_2, and squares S_1,\,S_2,\, and S_3, shown below, combine to form a rectangle that is 3322 units wide and 2020 units high. What is the side length of S_2 in units?

  • A.

    651

  • B.

    655

  • C.

    656

  • D.

    662

  • E.

    666

Answer:A

Solution 1

Let the side length of each square S_k be s_k. Then, from the diagram, we can line up the top horizontal lengths of S_1, S_2, and S_3 to cover the top side of the large rectangle, so s_{1}+s_{2}+s_{3}=3322. Similarly, the short side of R_2 will be s_1-s_2, and lining this up with the left side of S_3 to cover the vertical side of the large rectangle gives s_{1}-s_{2}+s_{3}=2020. We subtract the second equation from the first to obtain 2s_{2}=1302, and thus s_{2}=\boxed{\textbf{(A) }651}.

 

Solution 2

Assuming that the problem is well-posed, it should be true in the particular case where S_1 \cong S_3 and R_1 \cong R_2. Let the sum of the side lengths of S_1 and S_3 be x, and let the length of square S_2 be y. We then have the system

\begin{cases}x+y =3322 \\x-y=2020\end{cases}

which we solve to determine y=\boxed{\textbf{(A) }651}.