2009 AMC 10A Problem 3

Attempt Problem 3 of the 2009 AMC 10A 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 2009 AMC 10A solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

Which of the following is equal to

$1 + \cfrac{1}{1 + \cfrac{1}{1 + 1}}?$

$\dfrac{5}{4}$

$\dfrac{3}{2}$

$\dfrac{5}{3}$

$2$

$3$

Answer: C

Concepts:continued fraction fraction

Difficulty rating: 870

Solution:

Working outward, $\begin{aligned} &1 + \cfrac{1}{1 + \cfrac{1}{1 + 1}} \\ &= 1 + \cfrac{1}{1 + \dfrac{1}{2}} \\ &= 1 + \dfrac{1}{\frac{3}{2}} \\ &= 1 + \dfrac{2}{3} = \dfrac{5}{3}. \end{aligned}$

Thus, the correct answer is C.

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