Classification / Odd One Out for the Assam Police Constable (AB & UB) Exam
Classification, also called Odd One Out, is a reasoning topic of the SLPRB Assam Police Constable (AB & UB) examination in which a group of words or numbers is given and the candidate must find the one that does not belong to the group. The questions need no general knowledge and no calculation, only the ability to find the common property of the group and then spot the member that lacks it. It is one of the quickest and surest topics for a prepared candidate. This page explains the common bases of classification, the worked examples, the method and the traps that cost marks. The material follows the standard reasoning reference books used for Assam recruitment examinations and is reviewed before it is published.
What the Topic Means
In classification all the items of a group except one share a common property, and the candidate must find the item that does not share it. The common property may be a category such as fruits, a part of speech, a colour, a pair of opposites, a relation of number such as square or prime, or a relation of letters such as a fixed shift. The answer is the item that breaks the property which all the others follow.
Common Bases of Classification
- Category: three fruits and one vegetable, three birds and one animal.
- Part of speech: three nouns and one verb, three adjectives and one adverb.
- Colour: three colours and one shape.
- Number rule: three perfect squares and one non-square, three primes and one composite.
- Letter rule: three pairs from the same shift and one from a different shift.
- Nature: three living things and one non-living thing.
- Relation: three pairs of workers and tools and one pick that does not fit.
A Step by Step Method
- Read all the items of the group before deciding.
- Look for a property shared by three of the items.
- Check whether the fourth item lacks that property.
- If no property is found, try the number rule or the letter rule.
- Mark the item that does not fit and confirm the others do.
Worked Examples
Example one: Mango, Apple, Banana, Potato. Three are fruits and one is a vegetable, so Potato is the odd one out. Example two: 4, 9, 25, 30. Three are perfect squares and 30 is not, so 30 is the odd one out. Example three: CE, GI, KM, LM. In the first three pairs each letter is two places ahead of the other, while in LM they are consecutive, so LM is the odd one out. Example four: Doctor, Nurse, Teacher, Hospital. Three are persons and one is a place, so Hospital is the odd one out.
How This Topic Appears in the Examination
The topic usually appears as two to four objective questions of one mark each. The common forms are word classification, number classification and letter classification. The candidate must keep in mind that sometimes two answers seem possible, and then the property that is shared by three items in the clearest way is chosen.
Shortcuts and Speed Methods
- Look for the property shared by three before looking at the fourth.
- Try the category first, then the number rule, then the letter rule.
- For numbers, check square, cube, prime and divisibility.
- For letters, write the alphabet positions below the letters.
- If two items seem odd, choose the one that leaves a clear common property for the other three.
Common Mistakes to Avoid
- Choosing an odd item on a property that the other three do not clearly share.
- Reading the group in a hurry and missing the shared property.
- Confusing the category with a narrower class.
- Ignoring a possible number or letter rule.
- Not checking all the items before marking the answer.
Preparation Plan
- Learn the common bases of classification listed on this page.
- Practise twenty classification questions a day.
- Solve number and letter classification separately.
- Always confirm the property shared by the other items.
- Revise the common categories once a week.
More Practice Questions
- Cricket, Football, Hockey, Chess: Chess is played indoors and is not a field game in the same way, so it is the odd one.
- 2, 3, 5, 9: three are prime numbers and 9 is composite, so 9 is the odd one.
- Rose, Lotus, Lily, Mango: three are flowers and one is a fruit, so Mango is the odd one.
- BD, DF, FH, HI: in the first three, consecutive letters are two apart, while H and I are one apart, so HI is the odd one.
- Copper, Iron, Silver, Plastic: three are metals and one is not, so Plastic is the odd one.
Quick Revision Checklist
- Category, part of speech and colour.
- Number rules: square, cube and prime.
- Letter rules: shift and position.
- Living and non-living, persons and places.
- Always confirm the property shared by the other three.
Frequently Asked Questions
What is classification in reasoning?
Classification, or odd one out, is a reasoning topic in which all the items of a group except one share a common property, and the candidate must find the item that does not share it.
What is the first step in solving an odd one out question?
Read all the items and look for a property that three of them share clearly, and then check whether the fourth item lacks that property.
What kinds of properties are used?
Category, part of speech, colour, living or non-living, number rules such as square and prime, and letter rules such as a fixed shift or a common position.
What if two items seem odd?
Choose the item that leaves the clearest common property for the other three. The odd item is the one that breaks the property shared by all the rest.
Is odd one out scoring in Assam Police?
Yes. The questions are short and are answered by finding one common property, so they are among the quickest and surest marks in the reasoning paper.