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2020 AMC 10B Problem 3

Problem 3 of 25EasierAlgebra

The ratio of ww to xx is 4:3,4:3, the ratio of yy to zz is 3:2,3:2, and the ratio of zz to xx is 1:6.1:6. What is the ratio of ww to y?y?

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Solution

The ratios give wx=43,yz=32,zx=16. \begin{aligned} &\frac wx=\frac43,\qquad \frac yz=\frac32, \\ &\quad \frac zx=\frac16. \end{aligned} Then wy=wxxzzy=43623=163. \begin{aligned} &\frac wy=\frac wx\cdot\frac xz\cdot\frac zy \\ &\quad =\frac43\cdot 6\cdot\frac23=\frac{16}{3}. \end{aligned} Therefore w:y=16:3.w:y=16:3. Thus, E is the correct answer.

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Concepts: ratio and proportion

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