Question

Morgan invested $4,200 into two accounts. One account paid 4% interest and the other paid 7.5% interest. She earned 7% interest on the total investment. How much money did she put in each account?

Answer 1

Answer:

The amount invested at 4% was $600

The amount invested at 7.5%  was $3,600

Step-by-step explanation:

Let

x ----> the amount invested at 4%

$4,200-x -----> amount invested at 7.5%

we know that

The total interest earned is equal to the interest earned by the amount invested at 4% plus the interest earned by the amount invested at 7.5%

Remember that

$4\%=4/100=0.04$

$7.5\%=7.5/100=0.075$

$7\%=7/100=0.07$

so

The linear equation that represent this situation is

$0.04x+0.075(4,200-x)=0.07(4,200)$

Solve for x

$0.04x+315-0.075x=294$

$0.075x-0.04x=315-294$

$0.035x=21$

$x=\ 600$

$\ 4,200-x=\ 3,600$

therefore

The amount invested at 4% was $600

The amount invested at 7.5%  was $3,600