Sean invested $3,000 into two accounts. One account paid 4% interest and the other paid 8% interest. He earned 5% interest on the total investment. How much money did he put in each account?
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Answer:
1st investment with 8% is $750
2nd investment with 4% is 2250
Step-by-step explanation:
Here we have two equations with two unknowns. We know that amount 1, x, plus amount 2, y, is 3000. i.e.,
x + y = 3000
We also know that, when you add the interest earned on amount 1 to the interest earned on amount 2, the total interest is 5% of 3000, or 150.
i.e.
.08x + .04y = 150.
Now we use substitution so that each equation has only one variable. We learned in the first equation that x + y = 3000. When we subtract x from both sides to solve for y, we can see that y = 3000 - x. We then replace the y in the second equation with the right hand side of the one we just solved for y:
.08x + .04(3000 - x) = 150. Or:
.08x + 120 - .04x = 150
.04x = 30
Divide both sides by .04 to solve for x, and now we have
x = 750.
Now we simply plug this into our first equation and solve for y:
x + y = 3000
750 + y = 3000
y = 2250
So, $750 was placed in the account earning 8%, and $2,250 was placed in the account earning 4%.