Difference between revisions of "2011 AMC 8 Problems/Problem 11"

(Created page with "Average the differences between the two times. 10, -10, 20, 30, -20 The sum is 30. Divide by 5 = 6.")
 
(Copied down problem, but still needs solutions)
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Average the differences between the two times.
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The graph shows the number of minutes studied by both Asha (black bar) and Sasha (grey bar) in one week. On the average, how many more minutes per day did Sasha study than Asha?
10, -10, 20, 30, -20
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<asy>
The sum is 30.  Divide by 5 = 6.
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size(300);
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real i;
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defaultpen(linewidth(0.8));
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draw((0,140)--origin--(220,0));
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for(i=1;i<13;i=i+1) {
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draw((0,10*i)--(220,10*i));
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}
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label("$0$",origin,W);
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label("$20$",(0,20),W);
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label("$40$",(0,40),W);
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label("$60$",(0,60),W);
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label("$80$",(0,80),W);
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label("$100$",(0,100),W);
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label("$120$",(0,120),W);
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path MonD=(20,0)--(20,60)--(30,60)--(30,0)--cycle,MonL=(30,0)--(30,70)--(40,70)--(40,0)--cycle,TuesD=(60,0)--(60,90)--(70,90)--(70,0)--cycle,TuesL=(70,0)--(70,80)--(80,80)--(80,0)--cycle,WedD=(100,0)--(100,100)--(110,100)--(110,0)--cycle,WedL=(110,0)--(110,120)--(120,120)--(120,0)--cycle,ThurD=(140,0)--(140,80)--(150,80)--(150,0)--cycle,ThurL=(150,0)--(150,110)--(160,110)--(160,0)--cycle,FriD=(180,0)--(180,70)--(190,70)--(190,0)--cycle,FriL=(190,0)--(190,50)--(200,50)--(200,0)--cycle;
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fill(MonD,grey);
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fill(MonL,lightgrey);
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fill(TuesD,grey);
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fill(TuesL,lightgrey);
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fill(WedD,grey);
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fill(WedL,lightgrey);
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fill(ThurD,grey);
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fill(ThurL,lightgrey);
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fill(FriD,grey);
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fill(FriL,lightgrey);
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draw(MonD^^MonL^^TuesD^^TuesL^^WedD^^WedL^^ThurD^^ThurL^^FriD^^FriL);
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label("M",(30,-5),S);
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label("Tu",(70,-5),S);
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label("W",(110,-5),S);
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label("Th",(150,-5),S);
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label("F",(190,-5),S);
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label("M",(-25,85),W);
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label("I",(-27,75),W);
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label("N",(-25,65),W);
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label("U",(-25,55),W);
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label("T",(-25,45),W);
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label("E",(-25,35),W);
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label("S",(-26,25),W);</asy>
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<math> \textbf{(A)}\ 6\qquad\textbf{(B)}\ 8\qquad\textbf{(C)}\ 9\qquad\textbf{(D)}\ 10\qquad\textbf{(E)}\ 12 </math>
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==See Also==
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{{AMC8 box|year=2010|num-b=24|after=Last Problem}}

Revision as of 17:48, 4 November 2012

The graph shows the number of minutes studied by both Asha (black bar) and Sasha (grey bar) in one week. On the average, how many more minutes per day did Sasha study than Asha? [asy] size(300); real i; defaultpen(linewidth(0.8)); draw((0,140)--origin--(220,0)); for(i=1;i<13;i=i+1) { draw((0,10*i)--(220,10*i)); } label("$0$",origin,W); label("$20$",(0,20),W); label("$40$",(0,40),W); label("$60$",(0,60),W); label("$80$",(0,80),W); label("$100$",(0,100),W); label("$120$",(0,120),W); path MonD=(20,0)--(20,60)--(30,60)--(30,0)--cycle,MonL=(30,0)--(30,70)--(40,70)--(40,0)--cycle,TuesD=(60,0)--(60,90)--(70,90)--(70,0)--cycle,TuesL=(70,0)--(70,80)--(80,80)--(80,0)--cycle,WedD=(100,0)--(100,100)--(110,100)--(110,0)--cycle,WedL=(110,0)--(110,120)--(120,120)--(120,0)--cycle,ThurD=(140,0)--(140,80)--(150,80)--(150,0)--cycle,ThurL=(150,0)--(150,110)--(160,110)--(160,0)--cycle,FriD=(180,0)--(180,70)--(190,70)--(190,0)--cycle,FriL=(190,0)--(190,50)--(200,50)--(200,0)--cycle; fill(MonD,grey); fill(MonL,lightgrey); fill(TuesD,grey); fill(TuesL,lightgrey); fill(WedD,grey); fill(WedL,lightgrey); fill(ThurD,grey); fill(ThurL,lightgrey); fill(FriD,grey); fill(FriL,lightgrey); draw(MonD^^MonL^^TuesD^^TuesL^^WedD^^WedL^^ThurD^^ThurL^^FriD^^FriL); label("M",(30,-5),S); label("Tu",(70,-5),S); label("W",(110,-5),S); label("Th",(150,-5),S); label("F",(190,-5),S); label("M",(-25,85),W); label("I",(-27,75),W); label("N",(-25,65),W); label("U",(-25,55),W); label("T",(-25,45),W); label("E",(-25,35),W); label("S",(-26,25),W);[/asy]

$\textbf{(A)}\ 6\qquad\textbf{(B)}\ 8\qquad\textbf{(C)}\ 9\qquad\textbf{(D)}\ 10\qquad\textbf{(E)}\ 12$

See Also

2010 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 24
Followed by
Last Problem
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All AJHSME/AMC 8 Problems and Solutions
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