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Brad plans to invest a total of $6000, part of it in an account at 2% annual interest and the rest in an account at 8% annual interest. How much should he invest in each account so that the total interest in one year will be $192?

Respuesta :

Answer:

In an account at 2% invest [tex]\$4,800[/tex]

In an account at 8% invest [tex]\$1,200[/tex]

Step-by-step explanation:

we know that

The simple interest formula is equal to

[tex]A=P(1+rt)[/tex]

where

A is the Final Investment Value

P is the Principal amount of money to be invested

r is the rate of interest  

t is Number of Time Periods

in this problem we have  two cases

First case

[tex]t=1\ year\\ P=\$x\\ A=\$6,000+\$192=\$6,192\\r=0.02[/tex]

Second case

[tex]t=1\ year\\ P=\$6,000-\$x\\ A=\$6,000+\$192=\$6,192\\r=0.08[/tex]

substitute both cases in the formula above

[tex]\$6,192=\$x(1+(0.02*1))+(\$6,000-\$x)(1+(0.08*1))[/tex]

solve for x

[tex]6,192=x(1.02)+(6,000-x)(1.08)[/tex]

[tex]6,192=1.02x+6,480-1.08x[/tex]

[tex]1.08x-1.02x=6,480-6,192[/tex]

[tex]0.06x=288[/tex]

[tex]x=\$4,800[/tex]

so

In an account at 2% invest [tex]\$4,800[/tex]

In an account at 8% invest [tex]\$1,200[/tex]