Two investments were made totaling $15,000. For a certain year these investments yielded $1432 in simple interest...continued in description

Question

Two investments were made totaling $15,000. For a certain year these investments yielded $1432 in simple interest. Part of the $15,000 was invested at 9% and part at 10%. Find the amount invested at each rate.

Answer 1

Here's the formula: fv=p(1+int/c)^(tn)

fv future value

p premium

interest

c compound=1

t times/yr?

y yr?

Start with 7.5g to each %; add together. Put your % into decimal form (9%=.09). Adjust the times.

Answer 2

Let x = amount invested at 9%

Let y = amount invested at 10%

The 2 equations are:

x+y=15000

0.09x+0.10y=1432

Solve by any method, I chose substitution.

Solve the first equation for x by subtracting y from both sides

x+y-y=15000-y Simplify

x=15000-y

Substitute this into the second equation and solve

0.09(15000-y)+0.10y=1432 Distribute

1350-0.09y+0.10y=1432 Subtract 1350 from both sides and combine like terms

1350-0.09y+0.10y-1350=1432-1350 Simplify

0.01y=82 Divide both sides by 0.01

0.01y/0.01=82/0.01

y=8200

Now solve for x

x=15000-y

x=15000-8200

x=6800