You have already invested 400 in a stock with an annual retu

You have already invested $400 in a stock with an annual return of 11%. How much of an additional $1,400 should be invested at 12% and how much at 6% so that the total return on the entire $1,800 is 9%?

Solution

invested $400 in a stock with an annual return of 11%------400*0.11 =44

Let x be invested at 12 % ------0.12x

( 1400 -x) invested at 6% ----- ( 1400 -x)*0.06

So, + 400*0.11+ 0.12x +( 1400 -x)*0.06 = 1800*0.09

44+ 0.12x + 84 -0.06x = 162

0.06x + 128 = 162

0.06x = 34

x = $ 566.67 invested at 12 % and remaining $833.33 at 6%