Question 970699


Rhianna invests ${{{1200}}} in stock {{{s}}} and bonds {{{b}}}. 

The stock pays {{{9% }}} ={{{0.09}}} interest and the bonds pay {{{6%}}}={{{0.06}}} interest.


{{{.09s + .06b = 96}}}.........eq.1
{{{s + b = 1200}}}.........eq.2
----------------------------------------------------
from eq.2
{{{b = 1200-s}}}.......substitute in eq.1

{{{.09s+ .06(1200-s)  = 96}}}.............solve for {{{s}}}

{{{.09s+ 72-0.06s  = 96}}}

{{{.09s-0.06s  = 96-72}}}

{{{.03s  = 24}}}

{{{s  = 24/0.03}}}

{{{s  = 2400/3}}}

{{{s  = 800}}}

 If the total ANNUAL interest is ${{{I=96}}}, in the stock alone  is invested ${{{ highlight(800)}}}.

then, in the bond is  invested ${{{ 1200-800=400}}}

check:

The stock pays {{{9% }}} of ${{{ 800}}}:

${{{ 800*0.09=72}}}


The bond pays {{{6% }}} of ${{{ 400}}}:

${{{ 400*0.06=24}}}

then, {{{72+24=96}}} which confirms our solution


so, answer is 
D)
${{{800}}}