On Test Day, you're going to face a few questions in the Quant section that are perfect for "brute force" - you don't have to be a genius to get the correct answer and you don't need to have any specialized knowledge either. You DO have to put pen to pad and do some basic work though.
Here, we're asked for the total number of coins that Bert and Clair have.
Fact 1: Bert has 50 percent more coins than Claire.
Since you can't have a "fraction" of a coin, this piece of information provides just a little bit of info about the relationship between the number of coins that Bert has and the number of coins that Claire has.
Claire has 1 coin, Bert has 1.5 coins, which does NOT make sense (he can't have half a coin).
Claire has 2 coins, then Bert has 3 coins. THIS makes sense. The total is 5 coins.
Claire has 4 coins, then bert has 6 coins. This also makes sense. The total is 10 coins.
Fact 1 is INSUFFICIENT.
You may have noticed that the total number of coins is going to be a multiple of 5. You don't need to know that to answer the question (although it would likely save you some time later on).
Fact 2: The total number of coins that Bert and Claire have is between 21 and 28.
This gives us more direct information, but no exact value.
Fact 2 is INSUFFICIENT.
Combined, we know....
Bert has 50 percent more coins than Claire.
The total number of coins that Bert and Claire have is between 21 and 28.
From here, you can "map out" the possibilities....
We already know that Claire MUST have an EVEN number of coins....so let's start there....
Claire = 6, then Bert = 9 and the total is 15. This does not fit the given range, so it can't be the answer.
Claire = 8, then Bert = 12 and the total is 20. This does not fit the given range, so it can't be the answer.
Claire = 10, then Bert = 15 and the total is 25. This DOES fit the given range, so it COULD be the answer.
Claire = 12, then Bert = 18 and the total is 30. This does not fit the given range, so it can't be the answer.
As the number of coins Claire has increases, then the total will increase (and continue to be out of the given range). This means that there's JUST ONE answer that fits all of the given information.
GMAT assassins aren't born, they're made,
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