document.write( "Question 707181: Caroline Case won $60,000 on a slot machine in Las Vegas. She invested part of the money at 2% simple interest and the rest at 3%. In one year, she earned a total of $1600 in interest. How much was invested at the 3% rate?\r
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document.write( "Please explain step by step how to solve thiS! \n" );
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Algebra.Com's Answer #435614 by jim_thompson5910(35256)![]() ![]() ![]() You can put this solution on YOUR website! let x = amount invested at 2%, y = amount invested at 3%\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "She invested $60,000 total, so\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x+y = 60000\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "solve for y to get: y = 60000 - x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If she invests x dollars at 2% interest, then she will earn 0.02x dollars in interest alone after one year. Similarly, she will earn 0.03y dollars if she invests y dollars at 3%\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In total, she will earn 0.02x + 0.03y dollars in interest alone from both accounts combined.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We're told that \"In one year, she earned a total of $1600 in interest\", so \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Total Interest Earned = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.02x + 0.03y = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now plug in y = 60000 - x and solve for x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.02x + 0.03y = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.02x + 0.03(60000 - x) = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.02x + 0.03(60000) - 0.03x = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0.02x + 1800 - 0.03x = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-0.01x + 1800 = 1600\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-0.01x = 1600 - 1800\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "-0.01x = -200\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = -200/(-0.01)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 20000\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So $20,000 was invested at 2% simple interest\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = 60000 - x\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = 60000 - 20000\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "y = 40000\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "and $40,000 was invested at 3% simple interest\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Check: \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "we can see that the two amounts $20,000 and $40,000 add to $60,000, so that checks out\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "$20,000 invested at 2% gives you 20000*0.02*1 = 400 dollars in interest alone\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "$40,000 invested at 3% gives you 40000*0.03*1 = 1200 dollars in interest alone\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "In total, you get 400+1200 = 1600 dollars in interest alone\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So the answers are verified. \n" ); document.write( " |