document.write( "Question 1169802: 1. Please help again with these problems:at what compound interest rate per annum must money be invested if the principal must be tripled in 10 years and interest is calculated quarterly.
\n" ); document.write( "2. Use simultaneously equation to solve 5x-3y÷2=14, 2 dived on 3y and 5x÷6+5y=755, 6 dived on 5x \n" ); document.write( "
Algebra.Com's Answer #794649 by Boreal(15235)\"\" \"About 
You can put this solution on YOUR website!
P=Po(1+r/4)^40
\n" ); document.write( "P=3Po
\n" ); document.write( "3=(1+r/4)^40
\n" ); document.write( "ln 3=40 ln (1+r/4)
\n" ); document.write( "0.02747=ln(1+r/4)
\n" ); document.write( "raise to e power
\n" ); document.write( "1.0278=(1+(r/4))
\n" ); document.write( ".0278=r/4
\n" ); document.write( "r=11.12%\r
\n" ); document.write( "\n" ); document.write( "can check with rule of 110 for tripling of money (same approach as rule of 70 or 72 for doubling), which would say just over 10 years so answer reasonable.
\n" ); document.write( "-
\n" ); document.write( "5x-1.5y=14
\n" ); document.write( "(5x/6)+5y=755
\n" ); document.write( "multiply the top by 10 and bottom by 3
\n" ); document.write( "50x-15y=140
\n" ); document.write( "2.5x+15y=2265
\n" ); document.write( "52.5x=2405
\n" ); document.write( "x=45.81 and substitute into the first to get y=143.37
\n" ); document.write( "These do check but I wonder whether my interpretation of the explanation was the same as the actual problem.
\n" ); document.write( " \n" ); document.write( "
\n" );