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Difference between revisions of "2016 AMC 8 Problems/Problem 3"

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==Solution==
 
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Solution (Dhman2727):
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We see that <math>80-70=10</math> and <math>90-70=20</math>.  We then find that <math>10+20=30</math>.  We want our average to be <math>70</math>, so we find <math>70-30=40</math>.  So our final answer is <math>\textbf{(A) }40</math>.

Revision as of 08:42, 23 November 2016

3. Four students take an exam. Three of their scores are $70, 80,$ and $90$. If the average of their four scores is $70$, then what is the remaining score?

$\textbf{(A) }40\qquad\textbf{(B) }50\qquad\textbf{(C) }55\qquad\textbf{(D) }60\qquad \textbf{(E) }70$

Solution

This problem needs a solution. If you have a solution for it, please help us out by adding it.


Solution (Dhman2727):

We see that $80-70=10$ and $90-70=20$. We then find that $10+20=30$. We want our average to be $70$, so we find $70-30=40$. So our final answer is $\textbf{(A) }40$.

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