How much money did she invest in each account?

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horrible_at_tests

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i have been trying to figure this question out all day but i havent been able to :cry:

Melanie saved $1200 from working last summer. She invested sime of the money in a guaranted investment cerificate that paid 4.5% interest. Melanie deposited the rest in a savings account that paid only 2% interest. The total interest for the year was $40. How much money did Melanie invest in each?

any ideas would be great! :!: i dont have any ideas how to do this :(
 
Let x=amount saved at 4.5%.

\(\displaystyle \L\\.045x+.02(1200-x)=40\)

Solve for x.
 
lol sorry :p i hate math so much, i was able to do it up till grade9 and i see that kind of question and its like i freeze i dont no what to do lol, so ya lol my mouth like dropped when i saw how fast someone gave me that equation and i am very thankful for you helping me, i have been trying to figure it out for the longest time :p
 
Re: help! PLEASE!! :'(

horrible_at_tests said:
i have been trying to figure this question out all day but i havent been able to :cry:

Melanie saved $1200 from working last summer. She invested sime of the money in a guaranted investment cerificate that paid 4.5% interest. Melanie depositedthe rest in a savings account that paid only 2% interest. The total interest for the year was $40. How much money did Melanie invest in each?


any ideas would be great! :!: i dont have any ideas how to do this :(
Click to expand...

There's nothing magic about this at all....but you might think so because someone came up with an equation very quickly. YOU CAN DO THAT TOO!!

Choose a variable to represent one of the things you don't know....

for example,

let x = amount invested at 4.5%

Ok...now THINK!

She has a total of $1200 (her summer earnings) to invest. If she invests x dollars at 4.5%, then she has 1200 - x dollars to invest some other way. Suppose she choses to invest this amount at 2%.

You did not say (but I will assume) that each account pays simple interest. You should have access to the formula for simple interest:

Interest = (amount invested) * (interest rate expressed as a decimal) * (number of years)

We know that the time is 1 year in each case.

For the investment at 4.5% for 1 year,
Interest = x * (0.045)*1
Interest = .045x

For the investment at 2% for 1 year,
interest = (1200 - x) * (0.02)*1
interest = (1200 - x) * 0.02

And....the total interest earned is $40.....

interest earned at 4.5% + interest earned at 2.5% is $40

.045x + .02(1200 - x) = 40

Now...solve for x.

See, if you think it through in steps, it's not that bad.
 
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