Math Word Problems Demystified - A Self Teaching Guide

0 : 15 x¼ 315

0 : 151 x

0 : 151

¼

315

0 : 15

x¼ 2100

2 x¼ 2 ð 2100 Þ¼ 4200

Hence the person has $2100 invested at 3% and $4200 invested at 6%.

EVALUATION: Find the interest earned on each investment, then add, and
see if the sum is $315. UseI¼PRTwhereT¼1.

First investment:I¼ 3 %ð$ 2100 Þ¼$ 63

Second investment:I¼ 6 %ð 4200 Þ¼$ 252

$ 63 þ$ 252 ¼$ 315

EXAMPLE:An investor has $800 more invested in stocks paying 5% than
she has invested in bonds paying 4%. If the total interest is $103, find the
amount of money invested in each.

SOLUTION:

GOAL: You are being asked to find the amount of each investment.

STRATEGY: Letx¼the amount invested in the bonds andxþ 800 ¼the
amount invested in stocks.

Principal  Rate ¼ Interest

Bonds x 4% 4%(x)

Stocks xþ 800 5% 5%(xþ800)

The equation is 4%xþ5%(xþ800)¼$103.

LESSON 15 Solving Finance Problems 163