Math Word Problems Demystified - A Self Teaching Guide

 0 : 0251 x


 0 : 0251

¼

80

0 : 025

x¼$3200 invested at 4%

5000 
x¼ 5000 
 3200 ¼$1800 invested at 6

1

2

%

EVALUATION: Find the interest on both investments separately and then

add them up to see if they equal $245. UseI¼PRTwhereT¼1.

First investment:I¼$ 3200 ð 4 %Þ¼$ 128

Second investment:I¼$ 1800 ð 6

1

2

%Þ¼$ 117

$ 128 þ$ 117 ¼$ 245

EXAMPLE:A person has twice as much money invested at 6% as he has at

3%. If the total annual interest from the investments is $315, how much does

he have invested at each rate?

SOLUTION:

GOAL: You are being asked to find how much money is invested at 6%

and 3%.

STRATEGY: Letx¼the amount of money invested at 3% and 2x¼the

amount of money invested at 6%; then

Principal  Rate ¼ Interest

First investment 2 x 6% 6%(2x)

Second investment x 3% 3%(x)

The equation is 6%(2x)þ3%(x)¼$315.

IMPLEMENTATION: Solve the equation:

0 : 06 ð 2 xÞþ 0 : 03 ðxÞ¼ 315

0 : 12 xþ 0 : 03 x¼ 315

162 LESSON 15 Solving Finance Problems