document.write( "Question 1084512: There are ten cards labelled 1 to 10. Jacky takes out two cards without replacing them. Find the probability that both show even numbers.\r
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document.write( "Thanks! Much appreciated. \n" );
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Algebra.Com's Answer #698604 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! For problems like these, I find it helps to make a table like this one (shown below): \n" ); document.write( " ![]() \n" ); document.write( "Table generated with Excel. Free alternative programs (such as OpenOffice) can do the same thing.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The top row represents the possible choices for the first draw. \n" ); document.write( "The left border of values represent the choices for the second draw. \n" ); document.write( "Any ordered pair of the form (x,y) represents a possible outcome for both cards. \n" ); document.write( "For instance, in cell D9 we have the ordered pair (x,y) = (2,7) meaning that x = 2 is the first value drawn and y = 7 is the next value. \n" ); document.write( "The other ordered pairs in the table are to be read in this similar way.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Note: Something like (x,y) = (2,2) is NOT possible because once we pick x = 2, we don't replace it. \n" ); document.write( "It would be impossible to draw '2' again so the choices for y would go from {1,2,3,4,5,6,7,8,9,10} to {1,3,4,5,6,7,8,9,10}. \n" ); document.write( "Whenever this sort of event happens, I will mark it as NA (as seen in the table above)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "----------------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now go through the table and record all of the instances where BOTH x and y are even numbers\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Here is that list of outcomes highlighted with double asterisks on each side \n" ); document.write( " ![]() \n" ); document.write( "That highlighted list of ordered pairs is\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(4,2) \n" ); document.write( "(6,2) \n" ); document.write( "(8,2) \n" ); document.write( "(10,2) \n" ); document.write( "(2,4) \n" ); document.write( "(6,4) \n" ); document.write( "(8,4) \n" ); document.write( "(10,4) \n" ); document.write( "(2,6) \n" ); document.write( "(4,6) \n" ); document.write( "(8,6) \n" ); document.write( "(10,6) \n" ); document.write( "(2,8) \n" ); document.write( "(4,8) \n" ); document.write( "(6,8) \n" ); document.write( "(10,8) \n" ); document.write( "(2,10) \n" ); document.write( "(4,10) \n" ); document.write( "(6,10) \n" ); document.write( "(8,10)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There are 20 values in the list above. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "There would be 10*10 = 100 outcomes if replacements were made, but no replacements are made meaning we have 10 copies of \"NA\" to subtract out. So we have 100-10 = 90 outcomes total.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Dividing the values (20 and 90) we get: 20/90 = 2/9 = 0.222222 = 22.2222%\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "---------------------------------------------------------------- \n" ); document.write( "---------------------------------------------------------------- \n" ); document.write( "Final Answer as a fraction: 2/9 (this is exact) \n" ); document.write( "Final Answer as a decimal value: 0.222222 (this is approximate) \n" ); document.write( "Final Answer as a percentage: 22.2222% (this is approximate)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Notes: \n" ); document.write( "* Use a calculator, or long division, to go from the fraction 2/9 to the decimal 0.222222 \n" ); document.write( "* To go from the decimal value to the percentage, move the decimal point 2 spots to the right. \n" ); document.write( "* The three answer formats all represent the same idea just expressed different ways. \n" ); document.write( " \n" ); document.write( " |