Data sufficiency (DS) is one of the most important parts of Quant Section of various competitive examinations like IBPS PO, SBI PO, LIC, RBI, CAT etc.
The Data Sufficiency questions do not require the exam aspirant to find the exact answer. Infact the only thing that they require is to determine whether the statements provided in the question contain enough information for answering it.
There is a great chance that in any exam, you will see at least 5 questions from this topic. That means, you should spend some time getting confident with these types of questions.
We have seen that a majority of aspirants try follow guess work to solve these data sufficiency questions. This is not the right approach. So instead of guessing, we should use certain tips and tricks to solve these questions.
The interesting part about DS type questions is that they only ask you whether the question can be solved with the help of information given in the statements. That simply means there is no need to solve that question completely and waste your precious time. So just answer these questions and do not even try to solve them .There are several common tricks.
Do not think in terms of "What will be the exact value?" or "Is it true or false?"
Instead, just focus on only one issue: "Is the information enough o answer the question?"
Example:
Directions:-
How much was the cost of Diamond Necklace in January 2000?
(1) In January 2010 the necklace was worth $10,000.
(2) Over the ten years 2000-2010, the necklace increased in value by 10% each 12 months.
Solution
Statement (1) is insufficient. You don't know the rate at which value has changed. You immediately know the answer must be B, C or E.
Statement (2) is insufficient. Without a value between 2000 and 2010, you can't calculate the value.
Using statements (1) and (2) together, you could calculate the value in 2000. Since you need both statements to find the value, the answer is option (C).
The trick: Don't do the calculation. For most "value" questions, you could calculate the value but calculations are a waste of time. The problem asks if there is enough information to answer the question, not for the actual answer.
A number of questions are based on “YES-NO” type data. See the statements and discard them on the basis of yes or no.
Example:
Is x divisible by 28?
Statement I: x is divisible by 20
Statement II: x is divisible by 84
Answer. Using statement I - x is divisible by 4 and 5
Using statement II - x is divisible by 3, 4 and 7.
By using both statements we can conclude that x is divisible by 28 (4*7), hence answer is C.
So now you have studied the question and analyzed the information given in, now is the time to analyze the statements given in the question. The key rule here “Read statements independently of each other”. Try to “forget” statement 1 before you move on to statement 2.
Don’t carry over any info from statement 1 when you read statement 2.
Example:
How many adults eat pizza in city X if all adults in city X either eat Pizza or Pasta?
(1) 75% of the 100,000 adults in city X eat Pasta.
(2) 75,000 adults in city X eat Pasta.
Solution
Statement (1) is sufficient. Taking a percent of a total population allows you to calculate the adults that eat pizza. (NO need to do the calculation.) You immediately know the answer is A or D.
Statement (2) is insufficient. Without the total population or other information, you can't calculate the number of adults eating pasta.
Since first statement alone is sufficient, the correct answer is option (A).
The trick: Keep the information from first statement and second statement as separate. Either the percentage or total population from first statement can make second statement sufficient.
Always read each statement separately.
When you read second statement, forget what you read in first statement so you can evaluate second statement alone.
The only time to combine the statements is when each of them is insufficient alone
This will help you to eliminate the statements quickly if you have something to compare with the information given.
Do this step with a focused mind.
If first statement is sufficient, eliminate B, C, and E.
You will now be left with only two options ie A and D.
In the same way If second statement is sufficient, eliminate A, C, and E.
You will now be left with only two options ie B and D.
Conversely if first statement is NOT sufficient, eliminate A and D
In the same if second statement is NOT sufficient, eliminate B and D.
In this way you can eliminate a number of options.
Key Point to Note: Don't remember the sequence of the options. Sometimes they may even change the sequence of the options. So always read the sequence of options in the exam.
This article is prepared by Amit Chaudhary, Education Consultant at MockBank.com, a Bengaluru based online test preparation company for government/PSU jobs.