Problema Solution

Two bond funds pay interest at rates that differ by 2%. Money invested for one year in the first fund earns $605 interest. The same amount invested in the other fund earns $715. Find the lower rate of interest

Answer provided by our tutors

let


r = the lower rate as a decimal, r>0


r + 0.02 = the higher rate as a decimal


P = the money invested


Money invested for one year in the first fund earns $605 interest:


r*P = 605


P = 605/r


The same amount invested in the other fund earns $715:


(r + 0.02)*P = 715


plug P = 605/r into the last equation:


(r + 0.02)(605/r) = 715


by solving we find:


r = 0.11


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the lower rate of interest is 0.11 or 11%.