Odd one out concept (Reasoning) Notes for RRB JE 2019

Reasoning is one of the most scoring subjects of RRB exams and all other competitive exams and one of the easiest chapter in this section is from "Classification - Odd One Out". If the candidate is able to apply his thinking ability properly, he can easily score well in these questions. In this article, we are covering all the possible concepts along with some questions from this from the topic "Classification - Odd One Out" which are asked in previous year papers of competitive exams.

Basic Concepts of Classification

• To ‘classify’ means to assign some particular characteristic to the various member/part of a group and identify them on the basis of those particular characteristics only.
• Classification questions aim to test the skills of a candidate in determining the features of various things and candidate has to answer which one is odd-one from the group of 4 options. The odd-one option shouldn’t possess the skill which must be common among other four options.
• Such questions are really scoring as they require minimum calculations (if verbal). So, let’s understand how to solve various types of ‘Classification’ questions.
• All we have to do is identify the common feature in the 3 option. There can be various types of patterns which can be found in Classification questions. Some of those patterns are:

This common feature must be unique, ascertainable, non-imaginary and must not be present in odd-one option. While solving these questions, one should have basic awareness about general knowledge including Science, Geography, History, Mathematics etc.

Different Types of Questions asked in Competition Exams 

1. Finding the Odd-Word : In such questions, four ‘meaningful’ words are given. These words can be found in dictionary. Apart from that, these have similar feature, based on that we’re supposed to find the odd-word. For example:

1. a) Treachery

b)Fraud

c)Deceit

d)Morbid

Answer: Here, we can see that all except Morbid are synonymous to each other as they all mean ‘falsehood’ while ‘morbid’ means ‘diseased’. So, here we should have good vocabulary to solve such questions.

2. a) Feeling

b) Joy

c) Anxiety

d)Anger

Answer: Here, Joy, Anxiety and  Anger are all the type of Feeling. And, Feeling is a generic(or general) term. To solve this, we need good knowledge of adjectives.

3. a) Skull

b)  Appendix

c) Pelvis

d) Fibula

Answer:Here, All except Appendix are bones. While Appendix is an organ made of muscle. To solve this, we need basic knowledge of science.

2. Finding the odd-pair of words: In such questions, four options are given. Each option has a pair of words (that can be found in dictionary & hence meaningful).  Each three pair depicts a relationship among each other and this relationship is common in all the four pairs but can’t be found in 4^th odd-one pair. We’re supposed to find that odd-pair which doesn’t possess that common relationship. For example,

1. a) Lion: Roar

b) Snake: Hiss

c) Frog: Bleat

d)  Bees: hum

Answer: In all the pairs, the second word is the sound made by the animal which is also the first word. But in the pair of frog: bleat, bleat is the sound made by sheep not frogs.

2. a) Protein: Marasmus

b) Sodium: rickets

c) Iodine: Goitre

d) Iron: Anemia

Answer: In all the pairs, the second word describes the diseases, caused by deficiency of element which is first word. But in the pair of Sodium: Rickets, Rickets is being caused by deficiency of Vitamin D not Sodium.

3. a) Valley: Depth

b) Good: bad

c) High: Low

d) Black: white

Answer: Here, all the pairs contain the words which are antonym i.e. they mean opposite of each other. But, Valley & Depth are synonym to each other.

3. Finding the odd number: In such questions, four numbers are given. Each of the 3 numbers have common features like they are prime numbers or odd numbers or all divisible by ‘7’ while the 4^th number isn’t so we have to identify that odd-number which doesn’t have the feature the other four numbers have. For example:

1. a) 145

b) 197

c) 257

d) 399

Answer: Here, all the numbers except 399 are of the form (Square + 1) like 257 ⇒ 16² + 1 But 399 ⇒ 398 + 1 ⇒ 398 isn’t the square of any number.

2. a) 3759

b) 2936

c) 6927

d) 4836

Answer: Here, in all the options the pattern depicted is like this: Like in 3759 ⇒ (7+9) = 2×(3+5) ⇒ 16 = 2 × 8 But 2936 isn’t following this pattern: (2+6) ≠ 2×(2+3)

3. a) 5698

b) 4321

c) 7963

d) 4232

Answer: Here, ‘4232’ is the only number where digits have been repeated while all other options have three different unique digits.

4. Finding the odd-pair of numbers: In such questions, four options are given. Each option has a pair of numbers. Each four pair depicts a relationship among each other and this relationship is common in all the three pairs but can’t be found in 4^th odd-one pair. We’re supposed to find that odd-pair which doesn’t possess that common relationship. For example

1. a) 140 - 45

b) 110 – 35

c) 100 – 30

d) 80 – 25

Answer: The pattern seen here is (first number – 5) ÷3= Second number. like 140 – 45 ⇒ (140 – 5) ÷ 3 = 45 But 100 – 30 ⇒ (100 – 5) ÷ 3 ≠ 30

2. a) 7: 26

b) 8: 30

c) 10: 35

d) 13: 44

Answer: Here, the pattern is: 2nd number = (1st number × 3) + 5 Like in 7: 26 ⇒ 26 = 7 × 3 + 5 = 26 but in case 8: 30 ⇒ 30 ≠ 8×3 + 5

3. a) 21-49

b) 24-64

c) 25-54

d) 81-36

Answer: 21 & 49 have 7 as common factor, 24 & 64 have 8 as common factor. 81 & 36 have 9 as a common factor while 25 & 54 have no common factor.

5. Finding the odd letters: In such types of questions, four options contain random group of letters. These random groups of letters have common pattern and this pattern is common in all the three options but can’t be found in 4th odd-one. We’re supposed to find that odd-one which doesn’t possess that common pattern. For example,

1. a) DECB

b) GDFE

c)HKIJ

d) JFHG

Answer: All except JFHG contain consecutive alphabets in random order.

2. a) ACZX

b) BDYW

c) EGVT

d) CEUS

Answer: In all the groups except CEUS, 1st and 3rd letters occupy the same position from the beginning & end of alphabetical series respectively.

This method might look a bit time-consuming. You might think “It’s better to solve those puzzles then going through such lengthy 4-5 questions”. But wait, we can make these questions solving easy too:

Step I: Gather all the questions you can on the topic of Classification. Go through the questions given in the BYJU'S Exam Prep app. Just gather all the questions from all the credible sources. Mind it, credible, because many sites/books give wrong answer to these questions and that can hamper your logical thinking.

Step II: After having selected bulk of questions, start practising the questions. Read the options, try answering without timing yourself. Check the answer, understand the logic. Start gradually and continue the practice.

Step III: After solving 50-100 questions, you’ll start getting comfortable with the types of question patterns. It will take you less time to decipher the pattern.

Step IV: After practicing hundreds of questions with the techniques described above, you’ll be able to attempt one classification question in hardly a minute, that too flawlessly. This is the mastery stage where you can solve any difficulty of statement-assumption, and classification becomes scoring section for you.