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17

Part of 2006 AMC 10

Problems(2)

2006 AMC 10 #17

Source:

8/20/2011
In rectangle ADEH ADEH, points B B and C C trisect AD \overline{AD}, and points G G and F F trisect HE \overline{HE}. In addition, AH \equal{} AC \equal{} 2. What is the area of quadrilateral WXYZ WXYZ shown in the figure?
[asy]defaultpen(linewidth(0.7));pointpen=black; pathpen=black; size(7cm); pair A,B,C,D,E,F,G,H,W,X,Y,Z; A=(0,2); B=(1,2); C=(2,2); D=(3,2); H=(0,0); G=(1,0); F=(2,0); E=(3,0); D('A',A, N); D('B',B,N); D('C',C,N); D('D',D,N); D('E',E,NE); D('F',F,NE); D('G',G,NW); D('H',H,NW); D(A--F); D(B--E); D(D--G); D(C--H); Z=IP(A--F, C--H); Y=IP(A--F, D--G); X=IP(B--E,D--G); W=IP(B--E,C--H); D('W',W,N); D('X',X,plain.E); D('Y',Y,S); D('Z',Z,plain.W); D(A--D--E--H--cycle);[/asy]
<spanclass=latexbold>(A)</span>12<spanclass=latexbold>(B)</span>22<spanclass=latexbold>(C)</span>32<spanclass=latexbold>(D)</span>223<spanclass=latexbold>(E)</span>233 <span class='latex-bold'>(A) </span> \frac 12 \qquad <span class='latex-bold'>(B) </span> \frac {\sqrt {2}}2\qquad <span class='latex-bold'>(C) </span> \frac {\sqrt {3}}2 \qquad <span class='latex-bold'>(D) </span> \frac {2\sqrt {2}}3 \qquad <span class='latex-bold'>(E) </span> \frac {2\sqrt {3}}3
geometryrectanglecongruent triangles
Choosing balls

Source: AMC 10 2006B, Problem 17

2/17/2006
Bob and Alice each have a bag that contains one ball of each of the colors blue, green, orange, red, and violet. Alice randomly selects one ball from her bag and puts it into Bob's bag. Bob then randomly selects one ball from his bag and puts it into Alice's bag. What is the probability that after this process, the contents of the two bags are the same? <spanclass=latexbold>(A)</span>110<spanclass=latexbold>(B)</span>16<spanclass=latexbold>(C)</span>15<spanclass=latexbold>(D)</span>13<spanclass=latexbold>(E)</span>12 <span class='latex-bold'>(A) </span> \frac 1{10} \qquad <span class='latex-bold'>(B) </span> \frac 16 \qquad <span class='latex-bold'>(C) </span> \frac 15 \qquad <span class='latex-bold'>(D) </span> \frac 13 \qquad <span class='latex-bold'>(E) </span> \frac 12
probabilitysymmetryAMC