document.write( "Question 1062142: Three fair six-sided number cubes, each with faces labeled 0,2,4,6,8,10 are all rolled. What is the probability that the sum of the numbers rolled is greater than 20? Express your answer with a common fraction. \n" ); document.write( "
Algebra.Com's Answer #676961 by Boreal(15235)![]() ![]() You can put this solution on YOUR website! Look at cube 1 \n" ); document.write( "10 \n" ); document.write( "Draw a table \n" ); document.write( "=0==2===4==6====8===10 \n" ); document.write( "0 \n" ); document.write( "2 \n" ); document.write( "4 \n" ); document.write( "6 \n" ); document.write( "8 \n" ); document.write( "10 \n" ); document.write( "If the first cube is 10, the second and third must sum to 12 or more. That is 2 and 10 in second row \n" ); document.write( "4, and 8 or 10 in the third row; 6 and 6,8,10 in the fourth row; 8 and 4,6,8,10 in the fifth row, and 10 and 2,4,6,8,10 in the last row. There are 15 possibilities out of the 36 combinations or 15/36 \n" ); document.write( "Multiply that by 1/6 chance first is 10, and the probability is 15/216. \n" ); document.write( "------------------- \n" ); document.write( "Make the first cube 8 with 1/6 probability. \n" ); document.write( "Now the pyramid of choices that work has shifted down so instead of 1,2,3,4,5 that work, it is 1,2,3,4 or 10 possibilities. The joint probability is 10/216 \n" ); document.write( "------------------ \n" ); document.write( "Make the first cube 6 with 1/6 probability and the rows that work have 1,2,3 choices or 6/36 probability. The joint probability is 6/216. \n" ); document.write( "----------------- \n" ); document.write( "Make the first cube 4 and there are only 1, 2 choices or 3/36 probability. That is 3/216 joint probability. \n" ); document.write( "---------------- \n" ); document.write( "Make the first cube 2, and there is only one choice, 10 and 10 with 1/36 probability and 1/216 joint probability. \n" ); document.write( "--------------- \n" ); document.write( "If the first cube is 0, there is no chance. \n" ); document.write( "The joint probabilities sum to 15+10+6+3+1 , with denominator 216. The answer is 35/216. \n" ); document.write( " |