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2005 AMC 12B Problem 2

Problem 2 of 25EasierAlgebra

A positive number xx has the property that x%x\% of xx is 4.4. What is x?x?

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Solution

The statement translates to x100⋅x=4, \dfrac{x}{100}\cdot x = 4, so x2=400.x^2 = 400. Since xx is positive, x=20.x = 20. Thus, the correct answer is D.

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Concepts: percentage · quadratic

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