Question

Michelle has half of her investments in a stock paying 9% dividend and the other half in a stock paying 11% interest if her total annual interest is 430 how much does she have invested?

Answer 1

Let the amount he invested at 9% = x

Let the amount he invested at 11% = y

He invested the same amount in both stocks, so x=y

Interest(i)=principle(p)*rate(r)*time(t), but unless they specify that the time is different than one, i=p*r.

So the amount of interest he gets at 9%= 0.09x

The amount of interest he gets at 11% = 0.11y

Add the two together and your interest is=430

Therefore your system of linear equations is:

x=y

0.09x + 0.11y=430

----------------Substitute the first equation into the second and you have:

0.09x+0.11(x)=430

0.2x=430

0.2x/0.2=430/0.2

x = $2,150 (the amount he invested at 9%)

y=x so y=$2,150 (the amount he invested at 11%)

Add the two investments together to find out how much he invested all together:

$2,150+$2,150 = $4,300 is the amount he has invested altogether.

Therefore the amount he invested on each are $2150 and $2150, while the total investment altogether = $4300