# Various do's and don'ts of Data Sufficiency

The process to solve the DS questions is a bit different from the process involved in solving the QA or LR/DI questions. There are certain key things that we should keep in mind before solving the DS questions. Let us look at them one by one:

# Understanding the options

This is the first step in solving the DS questions. One must go through the options and understand them clearly. Sometimes, the options given in data set themselves can become a perennial source of problem.

Let us understand the statements given in the options:
If the option statement reads like — “If the question can be solved by using only one of the statements alone, but not by the other statement alone”.

Let us understand the statements given in the options:

# General awareness/assumptions are not allowed

As an unproclaimed rule, the element of general awareness cannot be used to solve the DS questions. However, this is also true for QA and LR /OI, but its importance in DS increases manifold.

Let us understand this with an example:

Let us understand this with an example:

Example

Is New Delhi the most polluted city in India?

Statement 1 – The Capital of India is the most polluted city in India.

Statement 2 – New Delhi is the capital.

Solution

Well, we can understand that statement 1 alone cannot answer the question, as it is not given that New Delhi is the capital of India.
If your answer is “Both the statements together can answer the question”, think again. It is not given in statement 2 that New Delhi is the capital of India.
So, answer to this question is “Cannot be determined.”
However, we should have a clear idea regarding the differences between a universal fact like “Pythagoras theorem” and general awareness like “New Delhi is the capital of India”.
Universal facts like mathematical principles are not the general awareness stuff, and hence can be used.

Example

In how many days A and B working together can finish a work?

Statement I— A can finish the same work alone in 10 days.

Statement 2— B can finish the same work alone in 15 days.

Solution

Understandably, we cannot have a unique answer to this question by using the statements alone. However, in this case we cannot solve this question even by using both the statement together.

**Flaw Detector**—Had this question been a question in Quantitative Aptitude, we must have got the answer by using the methods of time and work. However, in this case of data sufficiency, since it is not given that A and B start working together and kept on working together till the work is finished, we cannot solve this question even by using both the statements together. And we cannot make assumptions that they started working together and kept on working till the work is finished.