If then invests 3000 at 4 interest per year how much additio

If then invests $3000 at 4% interest per year, how much additional money must be invest at 5/12% annual interest to ensure that the interest receives each year is 41/2% of the total amount invested?

Solution

Ben invest $ 3000 at 4% rate

Interest after 1 year = 3000*4*1/100 = $120

Let additional amount invested be $x at 5.5% rate

Interest =   x*5.5*1/100 = 0.055x

Total interest ( 3000+x) at 4.5% rate

Interest = (3000+x)*4.5*1/100

120 + 0.055x = (3000+x)*4.5*1/100

120 +0.055x      = 135 + 0.045x

0.01x = 15

x = $ 1500 additional amount invested