Algebra Demystified 2nd Ed

Chapter 8 linear appliCaTionS 261

PRACTICE

1. A businessman invested $50,000 into two funds which yielded profits
   of 1621 % and 18%. If the total profit was $8520, how much was invested
   in each fund?


2. A college student deposited $3500 into two savings accounts, one with
   an annual yield of 434 % and the other with an annual yield of 514 %. If he
   earned $171.75 total interest the first year, how much was deposited in
   each account?


3. A banker plans to lend $48,000 at a simple interest rate of 16% and the
   remainder at 19%. How should she allot the loans in order to obtain a
   return of 1812 %?

✔SOLUTIONS

1. Let x represent the amount invested at 1612 %. Then 50,000 − x repre-
   sents the amount invested at 18%. The profit from the^1612 % account is
   0.165x, and the profit from the 18% investment is 0.18(50,000 − x). The
   sum of the profits is $8520.

0 165 01850000 8520

0 165 9000 0 180 85

..(, )

..

xx

xx

+−=

+− = 220

0 015 9000 8520

9000 9000

0 015 480

48

−+=

−−

−=−

= −

.

.

x

x

x^00

0 015

32 000

−

=

.

x ,

The amount invested at 1621 % is $32,000, and the amount invested at

18% is 50,000 − x = 50,000 − 32,000 = $18,000.

PRACTICE

1. A businessman invested $50,000 into two funds which yielded profits