19
Part of 2005 AMC 10
Problems(2)
Rotating a Square
Source:
1/14/2009
Three one-inch squares are palced with their bases on a line. The center square is lifted out and rotated , as shown. Then it is centered and lowered into its original location until it touches both of the adjoining squares. How many inches is the point from the line on which the bases of the original squares were placed?
[asy]unitsize(1inch);
defaultpen(linewidth(.8pt)+fontsize(8pt));draw((0,0)--((1/3) + 3*(1/2),0));
fill(((1/6) + (1/2),0)--((1/6) + (1/2),(1/2))--((1/6) + 1,(1/2))--((1/6) + 1,0)--cycle, rgb(.7,.7,.7));
draw(((1/6),0)--((1/6) + (1/2),0)--((1/6) + (1/2),(1/2))--((1/6),(1/2))--cycle);
draw(((1/6) + (1/2),0)--((1/6) + (1/2),(1/2))--((1/6) + 1,(1/2))--((1/6) + 1,0)--cycle);
draw(((1/6) + 1,0)--((1/6) + 1,(1/2))--((1/6) + (3/2),(1/2))--((1/6) + (3/2),0)--cycle);draw((2,0)--(2 + (1/3) + (3/2),0));
draw(((2/3) + (3/2),0)--((2/3) + 2,0)--((2/3) + 2,(1/2))--((2/3) + (3/2),(1/2))--cycle);
draw(((2/3) + (5/2),0)--((2/3) + (5/2),(1/2))--((2/3) + 3,(1/2))--((2/3) + 3,0)--cycle);label("",((1/6) + (1/2),(1/2)),NW);
label("",((2/3) + 2 + (1/4),(29/30)),NNE);draw(((1/6) + (1/2),(1/2)+0.05)..(1,.8)..((2/3) + 2 + (1/4)-.05,(29/30)),EndArrow(HookHead,3));fill(((2/3) + 2 + (1/4),(1/4))--((2/3) + (5/2) + (1/10),(1/2) + (1/9))--((2/3) + 2 + (1/4),(29/30))--((2/3) + 2 - (1/10),(1/2) + (1/9))--cycle, rgb(.7,.7,.7));
draw(((2/3) + 2 + (1/4),(1/4))--((2/3) + (5/2) + (1/10),(1/2) + (1/9))--((2/3) + 2 + (1/4),(29/30))--((2/3) + 2 - (1/10),(1/2) + (1/9))--cycle);[/asy] (A)\ 1\qquad (B)\ \sqrt {2}\qquad (C)\ \frac {3}{2}\qquad (D)\ \sqrt {2} \plus{} \frac {1}{2}\qquad (E)\ 2
rotationsymmetry
Difference between mean and median score
Source:
11/17/2005
On a certain math exam, of the students got 70 points, got 80 points, got 85 points, got 90 points, and the rest got 95 points. What is the difference between the mean and the median score on this exam?