Number Systems

[sukhman]

Symbol * denote to be one of the operations add, subtract, multiply, or divide. Is (6*2)*4=6*(2*4)?
1). 3*2>3 2). 3*1=3

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Hi sukhman,

For this type of symbolism question, we need to make sure to be thorough (that we've considered all the possibilities).

We're told that the symbol is 1 of 4 possible operations. We're asked if (6*2)*4 = 6*(2*4)? This is a Yes/No question.

Fact 1: 3*2 > 3

Here, the * symbol COULD be addition or multiplication

If it's addition, then (6+2)+4 DOES = 6+(2+4). The answer to the question is YES
If it's multiplication, then (6x2)4 DOES = 6(2X4). The answer to the question is YES.
Fact 1 is SUFFICIENT

Fact 2: 3*1 = 3

Here, the * symbol COULD be multiplication or division

From Fact 1, we know that multiplication gives us a YES answer.
If it's division, then (6/2)/4 = 3/4 and 6/(2/4) = 12 ..... 3/4 does NOT = 12, so the answer to the question is NO.
Fact 2 is INSUFFICIENT.

Final Answer: A

GMAT assassins aren't born, they're made,
Rich

[Brent@GMATPrepNow]

Symbol * denote to be one of the operations add, subtract, multiply, or divide.
Is (6*2)*4 = 6*(2*4)?
1) 3*2 > 3
2) 3*1 = 3

Target question: Does (6*2)*4 = 6*(2*4)?

Statement 1: 3*2 > 3
Check each operation.

Does * stand for addition?
3 + 2 > 3. So, * MIGHT denote addition

Does * stand for subtraction?
3 - 2 < 3. So, * does NOT denote subtraction

Multiplication?
3 x 2 > 3. So, * MIGHT denote multiplication

Division?
3/2 < 3. So, * does NOT denote division

So, * stands for EITHER addition OR multiplication
If * stands for addition, then (6*2)*4 EQUALS 6*(2*4)
If * stands for multiplication, then (6*2)*4 EQUALS 6*(2*4)
So, both cases yield the same answer to the target question (Yes).
Since we can answer the target question with certainty (the answer is YES), statement 1 is SUFFICIENT

Statement 2: 3*1 = 3

Does * stand for addition?
3 + 1 ≠ 3. So, * does NOT denote addition

Does * stand for subtraction?
3 - 1 ≠ 3. So, * does NOT denote subtraction

Multiplication?
3 x 1 = 3. So, * MIGHT denote multiplication

Division?
3/1 = 3. So, * MIGHT denote division

So, * stands for EITHER multiplication OR division
If * stands for multiplication, then (6*2)*4 EQUALS 6*(2*4)
If $ stands for division, then (6*2)*4 DOES NOT equal 6*(2*4)
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent