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2007 AMC 10A Problem 13

Problem 13 of 25IntermediateAlgebra

Yan is somewhere between his home and the stadium. To get to the stadium he can walk directly to the stadium, or else he can walk home and then ride his bicycle to the stadium. He rides 77 times as fast as he walks, and both choices require the same amount of time. What is the ratio of Yan’s distance from his home to his distance from the stadium?

Answer choices

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Solution

Let xx and yy be Yan’s distances from home and from the stadium, and let ww be his walking speed. Walking to the stadium takes yw.\dfrac{y}{w}. Walking home and biking takes xw+x+y7w.\dfrac{x}{w} + \dfrac{x + y}{7w}. Setting these equal gives 7y=8x+y,7y = 8x + y, so 8x=6y8x = 6y and xy=34.\dfrac{x}{y} = \dfrac{3}{4}. Thus, the correct answer is B.

More practice

Concepts: distance rate and time · ratio and proportion

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.