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Question 1171078: Astro Boy won $22 000 at a weight lifting competition. He decided to invest his money
in two different accounts. One fund earns 8.5% interest, the other earns 4% interest. If
Astro Boy earned $1 510 in interest in one year in total, how much was invested in each
account.
Found 2 solutions by Alan3354, greenestamps:
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Astro Boy won $22 000 at a weight lifting competition. He decided to invest his money in two different accounts. One fund earns 8.5% interest, the other earns 4% interest. If Astro Boy earned $1 510 in interest in one year in total, how much was invested in each account.
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Simple interest or compound?
If it's compound, you have to spec the compounding period.
Answer by greenestamps(13206)  (Show Source):
You can put this solution on YOUR website!
A setup for a formal algebraic solution....
x = amount invested at 8.5%
22000-x = amount invested at 4%
The total interest was $1510:
Solve using basic algebra... though the decimals make the calculations a bit unpleasant.
I leave it to you to finish the problem by that path.
Here is a method that gets you to the answer with what I think is far less effort....
(1) $22000 all invested at 8.5% would yield $1870 interest; all at 4% would yield $880 interest.
(2) Look at the three interest amounts on a number line -- 880, 1510, and 1870 -- and determine with simple calculations that $1510 is 630/990 = 7/11 of the way from $880 to $1870.
(3) That means 7/11 of the total was invested at the higher rate.
ANSWER: 7/11 of $22,000, or $14,000, was invested at 8.5%; the other $8000 at 4%.
CHECK: .085(14000)+.04(8000) = 1190+320 = 1510
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