SOLUTION: Every two years the value of a $225 investment at CIBC grows by $50. At RBC, a $150 investment grows by $90 every 3 years. Use a graphical method to determine when the investments

Algebra ->  Linear-equations -> SOLUTION: Every two years the value of a $225 investment at CIBC grows by $50. At RBC, a $150 investment grows by $90 every 3 years. Use a graphical method to determine when the investments       Log On


   

Question 971766: Every two years the value of a $225 investment at CIBC grows by $50. At RBC, a $150 investment grows by $90 every 3 years. Use a graphical method to determine when the investments are worth the same value.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Every two years the value of a $225 investment at CIBC grows by $50.
At RBC, a $150 investment grows by $90 every 3 years.
Use a graphical method to determine when the investments are worth the same value.
:
Assume the 1st investments will grows $25 a yr, the 2nd investment by $30 a yr
:
Let x = no. of yrs invested
let y = accumulated value of the investments
:
Write an equation for each
y = 25x + 225
and
y = 30x + 150
:
plot these two equations
+graph%28+300%2C+200%2C+-6%2C+25%2C+-100%2C+1000%2C+25x%2B225%2C+30x%2B150%29+
Looks like they intersect at x = 15, y looks like $600
:
you can confirm the point of intersection using the equations
30x + 150 = 25x + 225
30x - 25x = 225 - 150
5x = 75
x = 75/5
x = 15 yrs they will be equal
:
Their value then
y = 25(15) + 225
y = $600
the same with the other equation
y = 30(15) + 150
y = $600