Answer:
The amount invested at 8% rate is $1,200
The amount invested at 10% rate is $2,000
The amount invested at 12% rate is $3,500
Step-by-step explanation:
step 1
Let
x-----> the amount invested at 8% rate
y-----> the amount invested at 10% rate
z-----> the amount invested at 12% rate
----> equation A
----> equation B
substitute equation A in equation B
-----> equation C
we know that
The simple interest formula is equal to
where
I is the Final Interest Value
P is the Principal amount of money to be invested
r is the rate of interest
t is Number of Time Periods
in this problem we have
substitute in the formula above
substitute equation A
-----> equation D
step 2
Solve the system of equations
x+y=3,200 -----> equation C
-----> equation D
Solve the system by graphing
The solution is the point (1,200,2,000)
see the attached figure
Find the value of z
therefore
The amount invested at 8% rate is $1,200
The amount invested at 10% rate is $2,000
The amount invested at 12% rate is $3,500
