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In Episode 7 of our GMAT Ninja CR series, we are rounding up the oddballs, the misfits, and the format-benders: EXCEPT, Fill-In-The-Blanks, and other unusual Critical Reasoning question types. When you see a question that ends with a literal blank line
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For most test takers, Data Insights is the most challenging section on the GMAT, with test takers scoring several points lower on average on DI than on Quant or Verbal and completing the section with less time to spare. - Jun 10
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20 Sep 2021, 02:51
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Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
[\(x\)] is analyzed as follows.
If \(n ≤ x < n + 1\) for some integer n, then \([x] = n\).
Since we have \(1\) variable (\(x\)) and \(0\) equations, D is most likely to be the answer. So, we should consider each condition on its own first.
Condition 1)
\([x] = 2\)
\(=> 2 ≤ x < 3\)
Thus, condition 1) is not sufficient, since it does not yield a unique solution.
Condition 2)
Since there are a lot of integers, condition 2) does not yield a unique solution. This condition is not sufficient.
Conditions 1) & 2)
\(x = 2\) is the unique integer such that \(2 ≤ x < 3.\)
Thus, both conditions together are sufficient.
Therefore, C is the answer.
Answer: C
If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
22 Sep 2021, 02:11
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MathRevolution
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Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question.
Condition 2) tells us that \(2^x3^y=12 = 2^23^1\) and \(x = 2, y = 1.\)
Thus \(\frac{x}{y} = \frac{2}{1} = 2\), and condition 2) is sufficient.
Condition 1)
\(2^{x+y}3^{xy}=72 = 2^33^2\) yields the equations \(x+y=3\) and \(xy=2\).
So, \(x = 1\) and \(y = 2, or x =2\) and \(y = 1\).
Thus, \(\frac{x}{y} = \frac{1}{2}\) or \(\frac{x}{y} = \frac{2}{1} = 2\).
Condition 1) is not sufficient since it does not yield a unique solution.
Therefore, B is the answer.
Answer: B
25 Sep 2021, 03:42
Kudos
Bookmarks
MathRevolution
=>
Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question.
\(x^3-y^3 = (x-y)(x^2+xy+y^2)\)
Condition 1)
If \(x – y = 0\), then \(x^3-y^3 = (x-y)(x^2+xy+y^2) = 0.\)
Thus, condition 1) is sufficient.
Condition 2)
If \(x = 1\) and \(y = 1\), then \(x^3-y^3 = 1 – 1 = 0.\)
If \(x = 1\) and \(y = -1\), then \(x^3-y^3 = 1 –(-1) = 2.\)
Condition 2) is not sufficient since it does not yield a unique solution.
Therefore, A is the answer.
Answer: A
