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Data sufficiency

Quantitative Aptitude (RRB NTPC) Data Sufficiency

Data sufficiency

What is Data Sufficiency?

In questions based on Data Sufficiency, candidates are given a piece of information followed by a few conditions and then a few options where they have to answer which of the given conditions shall be necessary to answer the question.

As complicated as it may seem, the data sufficiency questions may be time taking at times because of their length and multiple options. Candidates need to ensure that they do not panic seeing the length of the question and guess the answer to the questions.

Tips and Tricks To Solve Data Sufficiency Questions

There are a few tips and tricks which can be followed to solve the data sufficiency questions. Candidates can refer to these tips given below:

Since the questions are lengthy, candidates must not panic and carefully read the entire question. At times, the different data sufficiency questions can also be solved verbally, especially for the quantitative aptitude questions
Do not look for the final answer (if not asked). You mostly have to only answer which conditions will satisfy your requirements to meet the answer to the question
Make sure that you do not make any assumptions. The information given in the question is the only fact that needs to be considered to answer the question
While going point by point, try solving the answer with the first condition given. Then, keep adding on the next conditions given until you get an answer
Generally, no data sufficiency question asked for a calculative answer. It mostly demands the candidates to know which conditions will help you reach the answer. So first read before answering

Solved Examples:

1. What is perimeter of the rectangle ?

I. Perimeter of square is 84 cm and length of rectangle is equal is equal to side of square.

II. The length of rectangle is 40% more than the breadth of rectangle.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, Side of square = 84/4 = 21cm

length of rectangle = 21

from II, let of breadth of rectangle = 5x

and length = 5x * 140/100 = 7x

from I and II both,

breadth of rectangle = 21/7x * 5x = 15

perimeter of rectangle = (21 + 15)2 = 72 cm

Both statement are required to find the answer.

2. What is the length of train ?

I. The train crosses a 220 meters long platform in 15 seconds.

II. The train crosses a person walking in opposite direction in 6 seconds.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, Let length of train = x

speed of train = y

x + 220/y = 15

From II, Let speed of man = z km/hr

x/y + z = 6

Both statement I and II are not sufficient to calculate the answer.

3. What is the rate of interest ?

I. Rs. 4000 becomes rs.5200 in 2 years when invested at simple interest.

II. The same sum is invested in CI and SI for 2 years at same rate of interest and difference between CI and SI is rs.90.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, Sum = 4000

2 years interest = 5200 – 4000 = 1200

1 years interest = 1200/2 = 600

rate of interest = 600/4000 * 100 = 15%

from II, P = 4000

difference = 90

90 = 4000 * R^2/1000^2

R = 15%

either I or II is sufficient.

4. What is the speed of boat in still water ?

I. Boat covers 150 km in upstream speed in 10 hours.

II. Ratio of speed of downstream and upstream is 5 : 3.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, Upstream speed = 150/10 = 15 km/hr

from II, Let downstream speed = 5x

upstream speed = 3x

from both I and II,

downstream speed = 15/3x * 5x = 25 km/hr

speed of boat = 25 + 15 /2 = 40/2 = 20 km/hr

Both statement are required to find the answer.

5. In how many days B alone can do the work ?

I. A and B together can complete a work is 18 days.

II. B and C together can complete the same work in 24 days.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

Alone statement I and II can not find answer

from both statement I and II together

LCM of 18 and 24 = 72

efficiency of A and B = 72/18 = 4

efficiency of B and C = 72/24 = 3

Here , we can not find individual efficiency so,

from both statement I and II we can not calculate the answer.

6. What is the area of square ?

I. The perimeter of square is 36 cm.

II. The area of rectangle is 96 cm^2 and side of square is 3 cm less than length of rectangular.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, perimeter of square is 36 cm.

side of square = 36/4 = 9 cm

area of square = 9 * 9 = 81 cm^2

From II, Area of rectangle = 96 cm^2

only from II we can not find the answer.

only statement I is sufficient.

7. How much profit earned selling a table ?

I. The ratio of cost price and marked price of the table is 5 : 8. After giving some discount profit percent occurred is 28%.

II. The shopkeeper is given 20% discount on MP and selling price of the table is rs.320.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I , Let CP of table = 5x

MP = 8x

profit = 28%

From II, SP = 320

discount = 20%

MP = 320/4 * 5 = 400

both From I and II,

MP = 400

CP = 400/8 * 5 = 250

profit = 320 – 250 = 70

Both I and II are sufficient to find answer.

8. What is profit share of C ?

I. A and B start the business with capital of rs.8000 and rs.10000 respectively.

II. After 4 months C joined the business with capital of rs.6000 and total profit at the end is rs 2200.

Only statement I is sufficient.
Only statement II is sufficient.
Either statement I or statement II is sufficient.
Neither statement I nor statement II is sufficient.
Both statement I and II are sufficient.

Solution:

From I, A and B invested rs.8000 and rs.10000 respectively.

from II, total profit = rs. 2200

C invested 6000 for 8 months

Both from I and II,

Profit sharing ratio of A, b and C = (8000 * 12) : (10000 * 12) : (6000 * 8)

= 4 : 5 : 2

profit of C = 2200 * 2/11 = 400

Both statement I and II is required to find answer.

9. What is the age of the mother of Rohit ?

I. The age of Rohit’s father is 3 times more than age of Rohit. After 4 years the ratio of age of Rohit and his father becomes 1: 3 and the age of mother is 4 years less than the age of his father.

II. The ratio of age of Rohit and his mother is 2 : 7 and before 4 years the age of Rohit and his mother 1 : 6.