document.write( "Question 1202960: A number is chosen at random from 1 to 600 inclusive. What is the probability that it will have at least 2 digits equal to 5? \n" ); document.write( "
Algebra.Com's Answer #838183 by math_tutor2020(3816)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Answer: 1/25\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Explanation:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let x be a number from the set {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In the case of 55x, there are 10 values possible \n" ); document.write( "550, 551, 552, 553, 554, 555, 556, 557, 558, 559\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The same goes for the 5x5 case \n" ); document.write( "505, 515, 525, 535, 545, 555, 565, 575, 585, 595 \n" ); document.write( "However notice how 555 has been repeated. \n" ); document.write( "This means we have really introduced 9 extra cases (not 10) to have 10+9 = 19 cases so far.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Then for the x55 case we have 6 more values, but we'll exclude 555 of course. \n" ); document.write( "55, 155, 255, 355, 455, 555 \n" ); document.write( "So we're adding 5 more cases to get 19+5 = 24 cases total\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Here are all 24 items arranged in a 6 row 4 column table \n" ); document.write( "
\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There are 24 values that have at least two digits of 5, out of 600 values total.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "24/600 = (1*24)/(25*24) = 1/25 is the fractional probability of getting such a value. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "1/25 = 0.04 in decimal form. \n" ); document.write( " \n" ); document.write( " |