# an investment

• September 6th 2010, 02:19 PM
aeroflix
an investment
an investment yields an annual interest of \$1500. If \$500 more is invested and the rate is 2% less, the annual interest is \$1300. What is the amount of investment and the rate of interest?
• September 6th 2010, 02:40 PM
pickslides
Sounds like a job for some simultaneous equations.

Given A is the initial amount invested, r is the rate then

Maybe use

(1+r)A= 1500+A ...(1)

and

(A+500)(1+(r-2))=1300+(A+500) ...(2)

Leaves you with some algebra.

I may be over complicating this one, it is early morning here!
• September 6th 2010, 02:45 PM
Soroban
Hello, aeroflix!

Quote:

An investment yields an annual interest of \$1500.
If \$500 more is invested and the rate is 2% less, the annual interest is \$1300.
What is the amount of investment and the rate of interest?

Let $x$ = amount invested.
Let $r$ = rate of interest.

We are told that $x$ dollars at $r$ percent yields \$1500.

. . Equation: . $rx \:=\:1500$

We are told that $(x+500)$ dollars at $(r-0.02)$ percent yields \$1300.

. . Equation: . $(x+500)(r-0.02) \:=\:1300$

Now solve the system of equations.

You will get a quadratic equation
and must discard one of the roots.
• September 8th 2010, 12:20 AM
aeroflix
thanks