Data Sufficiency - Introduction and Examples (with Solutions), Verbal Reasoning | UPSC Prelims Paper 2 CSAT - Quant, Verbal & Decision Making PDF Download

Data Sufficiency - Tips and Method

Data sufficiency is an important part of quantitative aptitude section of every competitive exam including IBPS, LIC, Civil services, CAT and GMAT. In almost every exam there are several questions from data sufficiency.

Most of the candidates try to solve data sufficiency questions by guess work. As every question carries same marks, questions in this part also deserve some time. Instead of guesswork use, a simple strategy as given below to avoid guessing the answer.

Steps in solving Data Sufficiency questions 

1) Read the given problem. Don't assume anything except universal facts.
2) Take the first statement and combine it with the main statement. Try to find the answer.
3) If you are unable to find the answer using 2nd step then combine the second statement and combine it with the main statement and try to find the answer.
4) If you are unable to find an answer using the second statement then add both statements with the main statement and try to find answer
5) If even now you can't find answer, simply tick both statements are insufficient.

Data Sufficiency - Directions to Solve
In each of the questions below consists of a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statements are sufficient to answer the question. Read both the statements and
Give answer
(A) If the data in statement I alone are sufficient to answer the question, while the data in statement II alone are not sufficient to answer the question
(B) If the data in statement II alone are sufficient to answer the question, while the data in statement I alone are not sufficient to answer the question
(C) If the data either in statement I alone or in statement II alone are sufficient to answer the question
(D) If the data given in both statements I and II together are not sufficient to answer the question and
(E) If the data in both statements I and II together are necessary to answer the question.

Sample Questions

Question: In which year was Rahul born?
Statements:
Rahul at present is 25 years younger to his mother.
Rahul's brother, who was born in 1964, is 35 years younger to his mother.
A.    I alone is sufficient while II alone is not sufficient
B.    II alone is sufficient while I alone is not sufficient
C.    Either I or II is sufficient
D.    Neither I nor II is sufficient
E.    Both I and II are sufficient

Answer: Option E

Explanation:

From both I and II, we find that Rahul is (35 - 25) = 10 years older than his brother, who was born in 1964. So, Rahul was born in 1954.

  
Question: What will be the total weight of 10 poles, each of the same weight?
Statements:
One-fourth of the weight of each pole is 5 kg.
The total weight of three poles is 20 kilograms more than the total weight of two poles.
A.    I alone is sufficient while II alone is not sufficient
B.    II alone is sufficient while I alone is not sufficient
C.    Either I or II is sufficient
D.    Neither I nor II is sufficient
E.    Both I and II are sufficient

Answer: Option C

Explanation:

From I, we conclude that weight of each pole = (4x5) kg = 20 kg.

So, total weight of 10 poles = (20 x 10) kg = 200 kg.

From II, we conclude that:

Weight of each pole = (weight of 3 poles) - (weight of 2 poles) = 20 kg.

So, total weight of 10 pojes = (20 x 10) kg = 200 kg.

Question: How many children does M have?
Statements:
H is the only daughter of X who is the wife of M.
K and J are brothers of M.
A.    I alone is sufficient while II alone is not sufficient
B.    II alone is sufficient while I alone is not sufficient
C.    Either I or II is sufficient
D.    Neither I nor II is sufficient
E.    Both I and II are sufficient

Answer: Option D

Explanation:

From I, we conclude that H is the only daughter of M. But this does not indicate that M has no son. The information given in II is immaterial.

Question: How much was the total sale of the company?
Statements:
The company sold 8000 units of product A each costing Rs. 25.
This company has no other product line.
A.    I alone is sufficient while II alone is not sufficient
B.    II alone is sufficient while I alone is not sufficient
C.    Either I or II is sufficient
D.    Neither I nor II is sufficient
E.    Both I and II are sufficient

Answer: Option E

Explanation:

From I, the total sale of product A = Rs. (8000 x 25) = Rs. 200000.

From II, we know that the company deals only in product A.

This implies that sale of product A is the total sale of the company, which is Rs. 200000.

Question: The last Sunday of March 2006 fell on which date?
Statements:
The first Sunday of that month fell on 5th.
The last day of that month was Friday.
A.    I alone is sufficient while II alone is not sufficient
B.    II alone is sufficient while I alone is not sufficient
C.    Either I or II is sufficient
D.    Neither I nor II is sufficient
E.    Both I and II are sufficient

Answer: Option C

Explanation:

From I, we conclude that 5th, 12th, 19th and 26th of March, 2006 were Sundays.

So, the last Sunday fell on 26th.

From II, we conclude that 31st March 2006 was Friday. Thus, 26th March 2006 was the last Sunday of the month.