Logical Reasoning - Logical Problems - Discussion

The logic problems in this set present you with three true statements: Fact 1, Fact 2, and Fact 3. Then, you are given three more statements (labeled I, II, and III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; all of the statements could be true; or none of the statements could be true. Choose your answer based solely on the information given in the first three facts.

4. 

Fact 1: All chickens are birds.
Fact 2: Some chickens are hens.
Fact 3: Female birds lay eggs.
If the first three statements are facts, which of the following statements must also be a fact?
I: All birds lay eggs.
II: Some Hens are birds.
III: Some chickens are not hens.

[A]. I only
[B]. II only
[C]. II and III only
[D]. None of the statements is a known fact.

Answer: Option C

Explanation:

The first statement cannot be true because only female birds lay eggs. Statement II is true because some hens are chickens and all chickens are birds. Statement III is also true because if only some chickens are hens, then some must not be hens.

Rahool said: (Nov 12, 2011)  
This is incorrect: If All chickens are birds & Some chickens are hens => all hens are birds; but the clue says only 'Some Hens are birds' what about the rest? they are also birds as per the facts given. So correct is statement [C] only.

Stankovic Hosea said: (Nov 21, 2011)  
Am not satisfied with number 4 because I think when they say "All chickens are birds", then all hens are birds as all hens are chickens.

Chandan said: (Sep 17, 2012)  
I think all hens are birds. Why option II is right?

Vipin said: (Jan 22, 2013)  
If some chickens are hens, that doesn't mean some chickens are not hens because in case all chickens are hens, we can also say that some chicken are hens. Hens we can't jump to such conclusions and so only II statement is correct.

Minender Singh said: (Jun 5, 2013)  
I think answer should be option no III only (some chickens are not hens) because :

1. All birds lay egg is not true because only female birds lay egg.

2. Some hens are birds is also not true because all chickens are bird.

3. Some chickens are not hens is true because statement says some chickens are hens. Hence rest other chicken not be hens.

Shikhar Dhami said: (May 31, 2014)  
I don't agree with it, I think the options itself is bit contradictory, taking example of option number II if you say some chickens are hen, that implies many chickens are not hens, hence statement II is incorrect, also option III cannot be implied from the given statements, because question says some chickens are birds, but doesn't say about the hen. If some chickens are hens that means all hens must be bird.

Ankit said: (Aug 25, 2014)  
Some chickens are hen does not imply that some are not chickens. Statement III is Incorrect.

Harman said: (Feb 4, 2015)  
I think statement 2 is incorrect, because all hens are bird.

Nirali said: (Mar 6, 2015)  
Only II is correct as we can never derive about NOT from the facts.

Daniel said: (Mar 20, 2015)  
Statement 1: Incorrect because all birds refers to both male and female birds and only female birds lay eggs.

Statement 2: Incorrect because of common sense and basic observation. No one has ever seen a hen that doesn't fall into anything other than the bird category in the animal kingdom.

Statement 3: Correct because of basic observation again.

Poki said: (Dec 3, 2015)  
The answers are absolutely right.

Goulal said: (Sep 12, 2016)  
Can anybody tell me the Logic and Reasoning?

Rsr said: (Oct 4, 2016)  
Only 2 is correct.

Himanshi R said: (Dec 6, 2016)  
Option B is correct.

You cannot convert some to some not because if you did that means From a single statement you are concluding many.

For ex: if you say all chickens are hens, we can also say that some chicken are hens which is true and it's converse some hens are chickens is also true.

Now,

According to your rule, some chicken are hens can also be said some chicken are not hens which is not possible since you cannot converse it plus there will be number of conclusions from a single statement.

Mauleka Jain said: (Feb 7, 2017)  
I think the only fact which is correct is III.

Jumanji said: (Dec 28, 2017)  
Earlier you talked about affirmative and negative sentences.

As in this question no negative sentence hence option 3 is wrong.

Answer should be option 2 only.

Manjari said: (Mar 18, 2018)  
I think 2 is the correct answer.

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