fangtray wrote:Joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy?
1. she bought $4.40 worth of stamps.
2. she bought an equal number of $0.15 stamps and $0.29 stamps.
I know the OA is A.
In this case, 15x + 29y =440, and we can solve for X and Y.
We can do this I assume, because x and y are integers. But is this ALWAYS the case? How can we spot on the exam when a linear equation will be solvable with 2 variables?
It's important to understand how the GMAT lays TRAPS.
1. She bought $4.40 worth of stamps.
2. She bought an equal number of $0.15 stamps and $0.29 stamps.
Clearly, the two statements combined provide sufficient information to determine how many 15-cent stamps were purchased.
Eliminate E.
Clearly, statement 2 does not by itself provide sufficient information.
If all we know is that Joanna purchased an equal number of each type of stamp, she could have purchased 1 of each type, 2 of each type, 3 of each type, etc.
Eliminate B and D.
The relationships described by the two statements are extremely straightforward.
If the OA here is C, then virtually EVERYONE will answer the question correctly, rendering the question pretty much useless.
Thus, the correct answer almost certainly is
A.
The best way to avoid TRAPS is to understand how the GMAT lays them.
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