Tricks to Data sufficiency Questions

Remember that data sufficiency questions do not require you to assume something and find an answer. They require you to determine ultimately whether sufficient data exist to answer the question. To answer a data sufficiency question, you do not need to find out the solution to each statement. You required to have a definitive answer.

1. Read the questions and don’t assume anything
2. Combine main statement with next statement and try to get answer.
3. Repeat step:2 until you complete all the statements and find an answer

Example: 

Choose1: if statement I alone is sufficient to answer the question

Choose2: if statement II alone is sufficient to answer the question

Choose3: if statement I and II together are sufficient to answer the question but neither statement alone is sufficient to answer the question

Consider three real numbers, A, B and C. Is C the smallest of these numbers?
I.    A is greater than at least one of B and C.
II.    B is greater than at least one of A and C.
a) 1          b) 2          c) 3          d) 4


Solution: (c)
From I, there are 4 possibilities:
               A>B>C,          A>C>B,          C>A>B,          B>A>C
Thus, I alone is not sufficient.
From II, there are 4 possibilities:
               B>A>C,          B>C>A,          A>B>C,          C>B>A
Thus, II alone is not sufficient.
Taking I and II together, we get
Either A>B>C or B>A>C
In both cases, C is smallest, hence option (c)

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