Maths Olympiad Prep

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Problem 543

Geometry Difficulty 2.5 Multiple choice CEMC Gauss (Grade 8) · Canada · 2015

There is a square whose perimeter is the same as the perimeter of the triangle shown.

Figure 0 The area of that square is

Pick one

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Official solution

The total value of one quarter, one dime and one nickel is 25+10+5=4025+10+5=40 ¢. Since you have equal numbers of quarters, dimes and nickels, you can separate your coins into piles, each containing exactly 1 quarter, 1 dime, and 1 nickel. Each pile has a value of 40¢, and since 440÷40=11440\div40=11, then you must have 11 quarters, 11 dimes and 11 nickels. Therefore, you have 11 dimes. Note: You can check that 11×(2511\times(25 ¢+10\,+ 10 ¢+5\,+5 ¢)=11×40)=11\times40 ¢ =440=440 ¢ =$4.40=\$4.40, as required.

Figure for this problem

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.