Expert: Paul Klarreich - 4/30/2007

Question
I just want to know how to write this in Algebra and not English :)  I need the formula or equation for this.

Bob now has two investments that produce a $150 income each month.  If $1,000 more is invested at 9% than at 10% per year, how much was invested at each percent?  There were 12 months in that year.

Answer
Questioner:   Boris
Category:  Advanced Math
Private:  No
 
Subject:  Word Problem Help
Question:  I just want to know how to write this in Algebra and not English :)  I need the formula

or equation for this.

Bob now has two investments that produce a $150 income each month.  If $1,000 more is invested at

9% than at 10% per year, how much was invested at each percent?  There were 12 months in that

year.
....................................
Hi, Boris,

This is a standard 'percent-mixture' problem, and you can set it up like this:

**************** VIEW IN COURIER FONT *****************
Investment     Amt Invested     Rate        Yield
------------+--------------+------------+------------
Risky bond          x           0.10        0.10x
Safe bond      x + 1000         0.09        0.09(x + 1000)
-----------------------------------------------------

The total yield is  150*12 = 1800 per year.  Therefore:

0.10x + 0.09(x + 1000) = 1800

Now clear the decimals, remove parentheses, then solve it.