MathDB
AMC 8 2008 Problem 19

Source:

November 28, 2010
probability

Problem Statement

Eight points are spaced around at intervals of one unit around a 2×22 \times 2 square, as shown. Two of the 88 points are chosen at random. What is the probability that the two points are one unit apart? [asy] size((50)); dot((5,0)); dot((5,5)); dot((0,5)); dot((-5,5)); dot((-5,0)); dot((-5,-5)); dot((0,-5)); dot((5,-5)); [/asy] <spanclass=latexbold>(A)</span> 14<spanclass=latexbold>(B)</span> 27<spanclass=latexbold>(C)</span> 411<spanclass=latexbold>(D)</span> 12<spanclass=latexbold>(E)</span> 47 <span class='latex-bold'>(A)</span>\ \frac{1}{4}\qquad<span class='latex-bold'>(B)</span>\ \frac{2}{7}\qquad<span class='latex-bold'>(C)</span>\ \frac{4}{11}\qquad<span class='latex-bold'>(D)</span>\ \frac{1}{2}\qquad<span class='latex-bold'>(E)</span>\ \frac{4}{7}