2014 AMC 12A Problem 1 — Solution | LIVE by Po-Shen Loh

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2014 AMC 12A Problem 1

Attempt Problem 1 of the 2014 AMC 12A 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 2014 AMC 12A solutions, or check the answer key.

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

1.

What is $10 \cdot \left(\dfrac{1}{2} + \dfrac{1}{5} + \dfrac{1}{10}\right)^{-1}?$

$3$

$8$

$\dfrac{25}{2}$

$\dfrac{170}{3}$

$170$

Answer: C

Concepts:fraction exponent

Difficulty rating: 870

Solution:

The sum inside the parentheses is $\dfrac12+\dfrac15+\dfrac{1}{10}=\dfrac{5+2+1}{10}=\dfrac{4}{5}.$

Its reciprocal is $\dfrac54,$ so the expression equals $10\cdot\dfrac54=\dfrac{25}{2}.$

Thus, the correct answer is C.

Problem 2#2 →

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