Art of Problem Solving

2025 AMC 10A Problems/Problem 2: Difference between revisions

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{{duplicate|[[2025 AMC 10A Problems/Problem 2|2025 AMC 10A #2]] and [[2025 AMC 12A Problems/Problem 2|2025 AMC 12A #2]]}}
#redirect [[2025 AMC 12A Problems/Problem 2]]
 
==Problem==
 
A box contains <imath>10</imath> pounds of a nut mix that is <imath>50</imath> percent peanuts, <imath>20</imath> percent cashews, and <imath>30</imath> percent almonds. A second nut mix containing <imath>20</imath> percent peanuts, <imath>40</imath> percent cashews, and <imath>40</imath> percent almonds is added to the box resulting in a new nut mix that is <imath>40</imath> percent peanuts. How many pounds of cashews are now in the box?
 
<imath>\textbf{(A)}~3.5\qquad\textbf{(B)}~4\qquad\textbf{(C)}~4.5\qquad\textbf{(D)}~5\qquad\textbf{(E)}~6</imath>
 
==Solution 1==
\documentclass{article}
\begin{document}
 
Since the first box had 5 pounds, and 50 percent off it had peanuts, we know there were 5 pounds of peanuts at the beginning. \\
Adding the second mixture of nuts, we call this value <imath>x</imath>, as in <imath>x</imath> pounds. \\
Of that 20\% or <imath>x/5</imath>, are peanuts. \\
Since the final percentage in 40 percent peanuts, <imath>(5 + x/5)/(10 + x) = 2/5</imath>. \\
Multiplying both sides by 5, we get, <imath>25 + x/10 + x = 2</imath>. \\
Multiplying both sides by <imath>10 + x</imath>, we get <imath>25 + x = 20 + 2x</imath>. \\
This gives us <imath>x = 5</imath>. \\
But the problem is asking us to solve for cashews. \\
The first mixture was <imath>1/5</imath> cashews, there were 2 cashews in the first mix. \\
In the second, there were <imath>2x/5</imath> cashews, or 2 pounds of cashews. \\
Adding this together gives us a final total of <imath>2 + 2 = \boxed{4}</imath> cashews.
 
\end{document}
~Minor edits to latex by WildSealVM/Vincent M.
 
==See Also==
{{AMC10 box|year=2025|ab=A|num-b=1|num-a=3}}
{{AMC12 box|year=2025|ab=A|num-b=1|num-a=3}}
* [[AMC 10]]
* [[AMC 10 Problems and Solutions]]
* [[Mathematics competitions]]
* [[Mathematics competition resources]]
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Latest revision as of 02:15, 8 November 2025