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
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Number Systems
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Target question: Does (6*2)*4 = 6*(2*4)?sukhman wrote: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
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
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Brent
Brent Hanneson - Creator of GMATPrepNow.com
