Question 1205201
<pre>
Assuming investment for 1 year

              SIMPLE INT. RATE     QUANTITY Inv.      INTEREST earned

SHORT             4%                      x            0.04x

INTERMED.         5%                      x            0.05x

LONG              6%                  100000-2x       0.06(100000-2x)
 
Total             5.1%                 100000                        
</pre>  
Total interest
{{{0.09x+0.06*100000-0.06*2x}}}
{{{0.09x-0.12x+6000}}}
{{{6000-0.03x}}}


Wanting effective rate 5.1%
{{{(6000-0.03x)/100000=0.051}}}

{{{6000-0.03x=5100}}}

{{{0.03x=6000-5100}}}

{{{0.03x=900}}}

{{{3x=90000}}}

{{{highlight(x=30000)}}}