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2016 Math Kangaroo

Problem 8

Problem 8 · 2016 Math Kangaroo Medium
Geometry & Measurement areaproportion

The rectangles S1 and S2 shown in the picture have the same area. Determine the ratio x : y.

Figure for Math Kangaroo 2016 Problem 8
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Answer: E — 8:5
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Hint 1 of 2
Write each rectangle's area from the lengths shown in the picture.
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Hint 2 of 2
Set the two areas equal and solve for x:y.
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Approach: equal-area condition from the figure
  1. From the diagram the two rectangles share the same area while one is short and tall and the other long and short.
  2. Setting their areas equal and simplifying the proportion gives x:y = 8:5.
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