Hi gmatmania17,
This DS question includes a great algebra "shortcut" that you'll be able to take advantage of a couple of times on Test Day.
We're told that $10,000 is broken into two banks accounts that return 8% interest and 10% interest over the course of one year. We're asked how much money was DEPOSITED into the 10% account.
To start, we can create an equation with 2 variables:
X = amount invested at 8%
Y = amount invested at 10%
X + Y = $10,000
This gives us 1 equation with 2 variables. We are asked to solve for the value of Y.
Fact 1: Total interest = $870
From this, we can create ANOTHER equation...
.08X + .1Y = $870
We now have a "system" of equations - 2 variables and 2 unique equations...which means that we CAN solve for X and Y. The shortcut here is that we DON'T have to - it's enough to know that we have enough information to get the answer, so we can stop working.
Fact 1 is SUFFICIENT
Fact 2: The amount invested at 10% was $3,000 less than the amount invested at 8%
From this, we can create ANOTHER equation...
Y = X - $3,000
As in Fact 1, we have a "system" of equations, so we have enough information and we can stop working.
Fact 2 is SUFFICIENT
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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