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Question

Three statements are given followed by three conclusions numbered I, II and Ill. Question ID: 264330143712 Status : Answered Chosen Option : 1 Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusions logically follow(s) from the statements.

Statements:

All males are boys.

Some teachers are boys.

All students are teachers.

Conclusions:

I. Some boys are males.

II. Some teachers are students.

Ill. All males are students.

The correct answer is

Only conclusions I and II follow

Solving the Syllogism: Statements and Conclusions

Let's analyze the given statements and conclusions to determine which conclusions logically follow. We can represent these statements using Venn diagrams or by analyzing the relationships directly.

Analysis of Statements

We have three statements:

  • Statement 1: All males are boys. ($\text{Males} \subset \text{Boys}$)
  • Statement 2: Some teachers are boys. (Intersection of $\text{Teachers}$ and $\text{Boys}$ is non-empty)
  • Statement 3: All students are teachers. ($\text{Students} \subset \text{Teachers}$)

From these statements, we can deduce some relationships:

  • Since All males are boys, the set of Males is a subset of the set of Boys.
  • There is an overlap between the set of Teachers and the set of Boys.
  • The set of Students is entirely contained within the set of Teachers.

Let's visualize the relationships based on the statements:

  • Set of Males is inside the set of Boys.
  • Set of Students is inside the set of Teachers.
  • Set of Teachers overlaps with the set of Boys.

Note that the overlap between Teachers and Boys could include individuals who are Students (since Students are Teachers) or individuals who are Teachers but not Students. The overlap could also include individuals who are Males (since Males are Boys) or individuals who are Boys but not Males.

Evaluating the Conclusions

Now let's examine each conclusion based on the statements:

Conclusion I: Some boys are males.

Statement 1 says "All males are boys". If all members of set A are members of set B, then it logically follows that some members of set B must be members of set A (specifically, the members of set A). For example, if all apples are fruits, then some fruits are apples. Thus, if All males are boys, then Some boys are males.

Conclusion I logically follows from Statement 1.

Conclusion II: Some teachers are students.

Statement 3 says "All students are teachers". Similar to Conclusion I, if all members of set A are members of set B, then it logically follows that some members of set B must be members of set A. If All students are teachers, then Some teachers are students.

Conclusion II logically follows from Statement 3.

Conclusion III: All males are students.

We know All males are boys. We know Some teachers are boys. We know All students are teachers. We need to determine if this forces all males to be students.

  • Males are inside the circle of Boys.
  • Students are inside the circle of Teachers.
  • Teachers and Boys circles overlap.

Consider a male. By Statement 1, this male is a boy. By Statement 2, some teachers are boys, meaning the intersection of Teachers and Boys is not empty. However, this doesn't tell us if the specific boy (who is a male) is a teacher. By Statement 3, all students are teachers. Even if a male boy is a teacher, he is not necessarily a student unless he falls into the specific subset of teachers who are students.

There is no statement or combination of statements that guarantees that every male is also a student. It is possible to construct a scenario where a male is a boy, this boy is also a teacher, but this teacher is not one of the teachers who is a student. It is also possible a male is a boy, but this boy is not among the "some boys" who are teachers.

Therefore, the conclusion "All males are students" does not logically follow from the given statements.

Conclusion III does not logically follow.

Summary of Conclusions

  • Conclusion I: Some boys are males. (Follows)
  • Conclusion II: Some teachers are students. (Follows)
  • Conclusion III: All males are students. (Does not follow)

Based on our analysis, only Conclusion I and Conclusion II logically follow from the given statements.

Conclusion Logically Follows? Reasoning
I. Some boys are males. Yes Derived from "All males are boys". If All A are B, Some B are A.
II. Some teachers are students. Yes Derived from "All students are teachers". If All A are B, Some B are A.
III. All males are students. No No direct connection established between All Males and All Students from the statements.

Revision Table: Syllogism Concepts

Concept Explanation Example
Universal Affirmative (All A are B) Every member of class A is a member of class B. All dogs are mammals.
Particular Affirmative (Some A are B) At least one member of class A is a member of class B. Some students are athletes.
Converse of "All A are B" "Some B are A". This is a valid inference. Converse of "All dogs are mammals" is "Some mammals are dogs".
Converse of "Some A are B" "Some B are A". This is a valid inference. Converse of "Some students are athletes" is "Some athletes are students".

Additional Information: Rules of Inference in Syllogisms

Understanding basic rules of inference helps in solving syllogism problems. Some key points:

  • From a universal statement ("All A are B"), a particular statement ("Some A are B") can be directly inferred. For example, if All humans are mortal, then Some humans are mortal.
  • The converse of a universal affirmative statement ("All A are B") is a particular affirmative statement ("Some B are A"). This is a valid inference.
  • The converse of a particular affirmative statement ("Some A are B") is also a particular affirmative statement ("Some B are A"). This is a valid inference.
  • It is generally not possible to infer a universal conclusion from two particular premises.
  • It is not possible to infer anything definite about the relationship between two sets if the middle term connecting them is qualified by "some" in both relevant statements. In this case, 'boys' connects 'males' (via All males are boys) and 'teachers' (via Some teachers are boys). We cannot reliably connect males and teachers universally or even particularly through 'boys' based on these statements alone.

Applying these principles confirms our evaluation of the conclusions.

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Important Questions from Conventional Syllogism

  1. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    No bank is an office.

    All offices are stalls.

    Conclusions:

    I. No bank is a stall.

    II. No stall is a bank.

    III. Some stalls are offices.

    IV. All the stalls are offices

  2. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    All flowers are beautiful.

    Vaidehi is beautiful.

    Conclusions:

    I. Vaidehi is a flower.

    II. Some beautiful are flowers.

  3. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    1. All rugs are blankets.

    2. All blankets are pillows.

    3. Some blankets are frames.

    Conclusions:

    I. All pillows are rugs.

    II. Some pillows are rugs.

    III. All rugs are frames

  4. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    Some fingers are toes.

    Some toes are rings.

    Some rings are hands.

    Conclusions:

    I. Some hands are toes.

    II. Some rings are fingers.

    III. Some hands are fingers.

    V. Some fingers are rings.

  5. Read the given statements and conclusions carefully. Assuming that the information given in the statements is true, even if it appears to be at variance with commonly known facts, decide which of the given conclusions logically follow(s) from the statements.

    Statements:

    All polygons are angles.

    All angles are diagonals.

    All cones are cubes.

    All cubes are decagons.

    No diagonal is a cube.

    Conclusions:

    I. Some diagonals are polygons.

    II. All diagonals are decagons.

    III. No polygon is a cone.

    IV. Some cubes are angles.

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