Difference between revisions of "2016 AMC 10A Problems/Problem 7"

(Added elements from matching 12A problem)
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== Solution ==
 
== Solution ==
  
As <math>x</math> is the mean, <cmath>x=\frac{60+100+x+40+50+200+90}{7}\implies x=\frac{540+x}{7}\implies 7x=540+x\implies x=\boxed{\textbf{(D) }90.}</cmath>
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As <math>x</math> is the mean, <cmath>\begin{align*}
 +
x=\frac{60+100+x+40+50+200+90}{7}
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&\implies x=\frac{540+x}{7} \\
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&\implies 7x=540+x \\
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&\implies 6x=540 \\
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&\implies x=\boxed{\textbf{(D) }90.}
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\end{align*}</cmath>
  
 
==See Also==
 
==See Also==
 
{{AMC10 box|year=2016|ab=A|num-b=6|num-a=8}}
 
{{AMC10 box|year=2016|ab=A|num-b=6|num-a=8}}
 +
{{AMC12 box|year=2016|ab=A|num-b=3|num-a=5}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 12:55, 4 February 2016

Problem

The mean, median, and mode of the $7$ data values $60, 100, x, 40, 50, 200, 90$ are all equal to $x$. What is the value of $x$?

$\textbf{(A)}\ 50 \qquad\textbf{(B)}\ 60 \qquad\textbf{(C)}\ 75 \qquad\textbf{(D)}\ 90 \qquad\textbf{(E)}\ 100$

Solution

As $x$ is the mean, \begin{align*} x=\frac{60+100+x+40+50+200+90}{7} &\implies x=\frac{540+x}{7} \\ &\implies 7x=540+x \\ &\implies 6x=540 \\ &\implies x=\boxed{\textbf{(D) }90.} \end{align*}

See Also

2016 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 6
Followed by
Problem 8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 10 Problems and Solutions
2016 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

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