Data Quant Sufficiency

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Theory

According to us, questions on Data Sufficiency are few of the trickiest in the entire IBPS PO paper. The good thing with Data Sufficiency is that there is no separate concept that needs to be learnt for solving Data Sufficiency questions. The flip side is that there is a lot of scope for committing mistakes in these questions. The most often committed mistake in Data Sufficiency is the assumption of data that is not mentioned in the question. For example, assuming the relationship mentioned in statement 1 while solving the question using statement 2, etc.

Tip

You do NOT have to solve a Data Sufficiency problem to get the answer. All you need to make sure is that a unique answer exists and that is derivable from the statements given.

Theory

Assume each condition individually when testing the first two options. Do not use conclusions drawn from using one statement with the other.

Tip

If you realize that the problem can be solved to give a UNIQUE solution, do not continue solving it.

Tip

Sometimes, the information given may look like it is enough to solve a problem. For example, two linear equations with two variables. In such a case, check that the equations are not inconsistent or do not give infinitely many answers.

Theory

The question can have different answers when the two statements are used separately. For example, if the question is about finding the value of ‘n’, and using statement 1 alone, the value is obtained as 1 and using statement 2 alone the value is obtained as 2, then the answer to the question is “The question can be answered using either statement alone” and not “The question cannot be answered”.

Tip

There is no one-best-way of solving a Data Sufficiency question. But, a good way of going about it is to first solve using statement 1 alone, then solve using statement 2 alone and then solve using both the statements together.

Tip

It is very important to solve the question using both the statements so as not to miss the option “The question can be answered by using either statement alone”.

Solved Example

Five friends P, Q, R, S and T are standing in a row facing north. Who is standing at the extreme left end?

Statement 1: Only P is between S and T. R is to the left of T
Statement 2: R is between T and Q.

a) The question can be answered by using statement 1 alone but not by using statement 2 alone
b) The question can be answered by using statement 2 alone but not by using statement 1 alone
c) The question can be answered by using either statement alone
d) The question can be answered by using both the statements together but not by using either statement alone
e) The question cannot be answered

Explanation:
Using statement 1 alone, there are many possibilities and we cannot answer the question. Using statement 2 alone also, we cannot answer the question since there are many possibilities.
Use both the statements together: From statement 2, R is between T and Q and from statement 1, R is to the left of T. So, Q R T are standing in that order.
From statement 1, only P is in between T and S. From all this information, the possibilities are:

Q R T P S; Q R S P T

In both the cases, Q is at the extreme left end of the row. So, the question can be answered by using both the statements together but not by using either statement alone.

Solved Example

What is the age of Rakesh?

Statement 1: Rakesh, Vimal and Sandeep are all of the same age
Statement 2: Total age of Vimal, Kunal and Sandeep is 32 years and Kunal is as old as Vimal and Sandeep put together.

Explanation:
Using statement 1 alone, we cannot answer the question.
Consider statement 2: Let the total age of Vimal and Sandeep be 2x. So, age of Kunal = 2x
=> 2x + 2x = 4x = 32 => x = 8

Now, use the information from both the statements: Vimal and Sandeep are of the same age => Each one of them is 8 years old. So, Rakesh is also 8 years old.

So, the question can be answered by using both the statements together but not by using either statement alone.

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