2020 AMC 12B Problem 3

Attempt Problem 3 of the 2020 AMC 12B below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2020 AMC 12B solutions, or check the answer key.

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The ratio of $w$ to $x$ is $4 : 3,$ the ratio of $y$ to $z$ is $3 : 2,$ and the ratio of $z$ to $x$ is $1 : 6.$ What is the ratio of $w$ to $y?$

$4 : 3$

$3 : 2$

$8 : 3$

$4 : 1$

$16 : 3$

Answer: E

Concepts:ratio and proportion

Difficulty rating: 1130

Solution:

Let $x = 6.$ From $z : x = 1 : 6,$ we get $z = 1.$ From $w : x = 4 : 3,$ we get $w = \tfrac43 \cdot 6 = 8.$ From $y : z = 3 : 2,$ we get $y = \tfrac32 \cdot 1 = \tfrac32.$

Therefore $w : y = 8 : \tfrac32 = 16 : 3.$

Thus, the correct answer is E.

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