I need math help involving quadratics?

Question

I got this question that I have no idea what to do with:
A man has $250,000. He has two bank accounts, one with 4% interest, the other with 5% interest. The bank with 4% interest earned him $3,286 more than the 5% interest account. How much money did he invest in each account?

Sorry to bug you with this everybody, but I really need help. I'm stumped =( It's for my summative assessment which is 15% of my final grade

Hey everybody! Thanks so much for your answers, they were so helpful! Thanks for the honesty too. I know I'm a little disoriented this semester

Answer 1

Sorry to say this to you brother,this is not a quadratic equation first of all.
You have 2 conditions:
Let money in bank with 5% interest be 'y'
and with 4% interest be 'x'.
then,x+y=2.5Lac...........(1)
interest= principle*no. of terms* rate of interest per term/100.
term be 1 year.
then 0.04x-0.05y=3286.
i.e. 4x-5y=3.286Lac...................(2)
from(1):
5x+5y=12.5Lac
4x-5y=3.286Lac
adding:
9x=15.786
thus,x=1.754 Lacs
and y=2.5-x (from(1))
y=0.746Lacs
You get the answer without any quadratic.........
brother study hard!!!
All the Best

Answer 2

I usually don't say things like this, but you're right -- you do need help. This problem doesn't involve quadratics.

If he invests x dollars in the 4% account, then he has (250,000 - x) left to invest in the 5% account.

Interest = Principal * rate * time, and you didn't mention a time frame, so I am going to assume it was for 1 year.

If we let y = the money earned from the 5% interst rate, then
y + 3286 = the money earned from the 4% account.

So we get two equations. First, for 4%,
y+3286 = x * 0.04

and second for the 5% account,
y = x * 0.05

Since this is for credit in one of your classes, I think that you should finish the rest: just use an elimnation method with the two equations and be sure that you give both answers that your question asked you for.

Hope this helps!

Answer 3

Since you didn't say too much about the details of the interest payments, I assumed this was interest for one year, compounded annually. If the time period or compounding was something else, then the method shown below is not right. But it's not quadratic...

Let X = amount of money in the 4% account
Y = amount of money in the 5% account

Since X+Y = 250,000, then Y = 250,000 - X, so we will use that expression as the amount of money in the 5% account.

.04X is the amount of INTEREST from the 4% account
.05(250000-X) is the amount of INTEREST from the 5% account

Therefore,

.04X = 3286 + .05(250000-X)
.04X = 3286 + 12500 - .05X
.09X = 15786
X = $175,400 (amt @ 4%)
250,000-175,400 = $74,600 (amt @5%)

Answer 4

This isn't quadratics. Draw a picture and think of the equation you use, which is
Interest= Principal x interest rate.
So if x is invested at 4 %, I4 = 0.04 * x
And if the rest (250000-x) is invested at 5%,
I5 = 0.05 * (250000-x)

You really don't need to know exactly what I4 and I5 are (this is the crux of the problem), since you know that I4 - I5 = 3286.

Now put it all together and get your answer.