document.write( "Question 578502: A, B, & C have equal incomes from investments. A has invested $2000 less than B and $2500 more than C . The rate of interest received by A is 1 per cent more than that received by B and 2 per cent less than that received by C. How much has A invested? Pls. help me solve this. I've been working on it for 2 hours now and still can't come up with the equation and the answer. Thanks. \n" ); document.write( "
Algebra.Com's Answer #370691 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! A, B, & C have equal incomes from investments. \n" ); document.write( "A has invested $2000 less than B and $2500 more than C . \n" ); document.write( " The rate of interest received by A is 1 per cent more than that received by B \n" ); document.write( " and 2 per cent less than that received by C. \n" ); document.write( " How much has A invested? \n" ); document.write( ": \n" ); document.write( "You're right, this is a doozy \n" ); document.write( ": \n" ); document.write( "Let A, B, C = amt of each investment \n" ); document.write( "Let a, b, c = interest rate of each in decimal form \n" ); document.write( ": \n" ); document.write( "Given that incomes are equal: \n" ); document.write( "aA = bB = cC \n" ); document.write( "Write an equation for each statement: \n" ); document.write( ": \n" ); document.write( "Get B and C in terms of A, and get b & c in terms of a \n" ); document.write( ": \n" ); document.write( "\" A has invested $2000 less than B.\" \n" ); document.write( "A = B-2000 \n" ); document.write( "or \n" ); document.write( "B = (A+2000) \n" ); document.write( "and \n" ); document.write( "\"$2500 more than C\" \n" ); document.write( "A = C+2500 \n" ); document.write( "or \n" ); document.write( "C = (A-2500) \n" ); document.write( ": \n" ); document.write( "\" The rate of interest received by A is 1 per cent more than that received by B\" \n" ); document.write( "a = b+.01 \n" ); document.write( "or \n" ); document.write( "b =(a-.01) \n" ); document.write( ": \n" ); document.write( "\"and 2 per cent less than that received by C.\" \n" ); document.write( "a = c-.02 \n" ); document.write( "or \n" ); document.write( "c = (a+.02) \n" ); document.write( ": \n" ); document.write( "We know \n" ); document.write( "aA = bB \n" ); document.write( "replace b with (a-.01) and B with (A+2000) \n" ); document.write( "aA = (a-.01)(A+2000) \n" ); document.write( "FOIL the right \n" ); document.write( "aA = aA + 2000a - .01A - 20 \n" ); document.write( "Subtract aA from both sides, add 20 to each side \n" ); document.write( "2000a - .01A = 20 \n" ); document.write( ": \n" ); document.write( "aA = cC \n" ); document.write( "replace c with (a+.02) and C with (A-2500) \n" ); document.write( "aA = (a+.02)(A-2500) \n" ); document.write( "FOIL the right \n" ); document.write( "aA = aA - 2500a + .02A - 50 \n" ); document.write( "Subtract aA from both sides, add 50 to each side \n" ); document.write( "-2500a + .02A = 50 \n" ); document.write( ": \n" ); document.write( "Use elimination with these two equation, multiply the 1st on by 2, add to the 2nd \n" ); document.write( "4000a - .02A = 40 \n" ); document.write( "-2500a +.20A = 50 \n" ); document.write( "-------------------adding eliminates A, find a \n" ); document.write( "1500a = 90 \n" ); document.write( "a = \n" ); document.write( "a = .06, so 6% is the int rate of the A investment \n" ); document.write( "then \n" ); document.write( "b = .06 - .01 \n" ); document.write( "b = .05, 5% is the int rate of the B investment \n" ); document.write( "and \n" ); document.write( "c = .06 +.02 \n" ); document.write( "c = .08, 8% is the int rate of the C investment \n" ); document.write( ": \n" ); document.write( "Remember aA = bB \n" ); document.write( ".06A = .05B \n" ); document.write( "Replace B with (B+2000) \n" ); document.write( ".06A = .05(A+2000) \n" ); document.write( ".06A = .05A + 100 \n" ); document.write( ".06A - .05A = 100 \n" ); document.write( ".01A = 100 \n" ); document.write( "A = \n" ); document.write( "A = $10,000 investment which is what they want \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "You can check this by finding the actual interest from B & C, confirming that they are all equal. I did this and found each had a return of $600, but don't take my word for it. C\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |