Math Word Problems Demystified - A Self Teaching Guide

8. An investor invested some money at 7% and some money at 5%.
   If the yearly interest on both investments is the same and the
   total amount of the investments is $12,000, find the amount of
   each investment.


9. Mr. Jordan has three investments. He has three times the amount of
   money invested at 4% as he has invested at 1% and $400 more
   invested at 3% as he has at 1%. If the yearly interest is $108, find
   the amount of each investment.


10. A person has $3000 invested at 6%. How much should he invest at
    4% to have an income (yearly) interest of $372?

SOLUTIONS:

1. Letx¼the amount of money invested at 7% and $12000
   x¼the
   amount of money invested at 5%.
   7 %xþ 5 %ð12,000
   xÞ¼ 760

0 : 07 xþ 0 : 05 ð12,000
xÞ¼ 760

0 : 07 xþ 600 
 0 : 05 x¼ 760

0 : 02 xþ 600 ¼ 760

0 : 02 xþ 600 
 600 ¼ 760 
 600

0 : 02 x¼ 160

0 : 021 x

0 : 021

¼

160

0 : 02

x¼$8000 at 7%

12,000
x¼12,000
 8000 ¼$4000 at 5%

2. Letx¼the amount of money invested at 4^12 % and $9000
   x¼the
   amount of money invested at 5%.

4

1

2

%xþ 5 %ð 9000 
xÞ¼$ 435

0 : 045 xþ 0 : 05 ð 9000 
xÞ¼ 435

0 : 045 xþ 450 
 0 : 05 x¼ 435


 0 : 005 xþ 450 ¼ 435


 0 : 005 xþ 450 
 450 ¼ 435 
 450

LESSON 15 Solving Finance Problems 167