Difference between revisions of "2010 AMC 12B Problems/Problem 6"

(Problem 6)
(Solution)
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== Solution ==
 
== Solution ==
Clearly, the minimum possible value would be <math>70 - 50 = 20\%</math>. The maximum possible value would be <math>30 + 50 = 80\%</math>. The difference is <math>80 - 20 = 60</math> <math>(D)</math>.
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Clearly, the minimum possible value would be <math>70 - 50 = 20\%</math>. The maximum possible value would be <math>30 + 50 = 80\%</math>. The difference is <math>80 - 20 = \boxed{60}</math> <math>(D)</math>.
  
 
== See also ==
 
== See also ==
 
{{AMC12 box|year=2010|num-b=5|num-a=7|ab=B}}
 
{{AMC12 box|year=2010|num-b=5|num-a=7|ab=B}}

Revision as of 16:58, 6 February 2013

Problem 6

At the beginning of the school year, $50\%$ of all students in Mr. Wells' math class answered "Yes" to the question "Do you love math", and $50\%$ answered "No." At the end of the school year, $70\%$ answered "Yes" and $30\%$ answered "No." Altogether, $x\%$ of the students gave a different answer at the beginning and end of the school year. What is the difference between the maximum and the minimum possible values of $x$?

$\textbf{(A)}\ 0 \qquad \textbf{(B)}\ 20 \qquad \textbf{(C)}\ 40 \qquad \textbf{(D)}\ 60 \qquad \textbf{(E)}\ 80$

Solution

Clearly, the minimum possible value would be $70 - 50 = 20\%$. The maximum possible value would be $30 + 50 = 80\%$. The difference is $80 - 20 = \boxed{60}$ $(D)$.

See also

2010 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 5
Followed by
Problem 7
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