document.write( "Question 1136030: Phyllis invested 43000dollars, a portion earning a simple interest rate of 5
\n" ); document.write( "percent per year and the rest earning a rate of 7
\n" ); document.write( "percent per year. After one year the total interest earned on these investments was 2430 dollars. How much money did she invest at each rate?\r
\n" ); document.write( "\n" ); document.write( "At rate 5percent :
\n" ); document.write( "At rate 7percent :
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Algebra.Com's Answer #753797 by greenestamps(13200)\"\" \"About 
You can put this solution on YOUR website!


\n" ); document.write( "Here is a completely different method without algebra which, if you understand how to use it, can get you to the answer to a problem like this much faster and with far less effort than traditional algebraic methods.

\n" ); document.write( "This is essentially a mixture problem -- you are mixing investments at 5% and 7% and receiving an overall percentage return somewhere between 5% and 7%.

\n" ); document.write( "The key to this method of solving mixture problems is that the ratio in which the total investment is split exactly determines where the overall percentage lies between the 5% and 7%.

\n" ); document.write( "$43,000 all at 5% would yield $2150 interest.
\n" ); document.write( "$43,000 all at 7% would yield $3010 interest.

\n" ); document.write( "Find where the actual interest of $2430 lies between $2150 and $3010:

\n" ); document.write( "3010-2150 = 860; 2430-2150 = 280; 280/860 = 28/86 = 14/43

\n" ); document.write( "Those simple calculations show that $2430 is 14/43 of the way from $2150 to $3010; that means 14/43 of the total investment was at the higher rate.

\n" ); document.write( "ANSWER: 14/43 of $43,000, or $14,000, at 7%; the rest, $29,000, at 5%.

\n" ); document.write( "CHECK: .07(14000)+.05(29000) = 980+1450 = 1430
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