Logical Reasoning - Logical Problems - Discussion

Each problem consists of three statements. Based on the first two statements, the third statement may be true, false, or uncertain.


Joe is younger than Kathy.
Mark was born after Joe.
Kathy is older than Mark.
If the first two statements are true, the third statement is

[A]. true
[B]. false
[C]. uncertain

Answer: Option A


Joe is younger than Kathy and older than Mark, so Mark must be younger than Kathy.

Ajit Singh said: (Apr 23, 2011)  
I am just not satisfied with the Answer. Per my understanding the answer should be C- Uncertain. Because Mark is older than Joe however it has not mentioned Kathy is older or younger than Kathy, So we cannot determined that Kathy is older than Mark.

Please provide your thoughts on this

Sundar said: (Apr 23, 2011)  
@Ajit Singh

Your answer is wrong. Let me explain in detail.

1. Joe(J) is younger than Kathy(K) = J < K
2. Mark(M) was born after Joe(J) = M < J

Combine 1 and 2, Result = M < J < K

3. Kathy(K) is older than Mark(M) = K > M (or) M < K

Now compare M < K (3rd statement) with the combined result of 1 and 2 i.e M < J < K.

M < K [compare] M < J < K

Clearly, it is TRUE. Hence the answer.

Hope this explanation may help you. Have a nice day!

Nik said: (May 6, 2011)  
Due how come u derived M<J ? If M is born after J then is it M < J or J < M ? Its funny

Fdfsd Df Sdfsd said: (Jul 25, 2011)  
In the Explanation:

"Joe is younger than Kathy and older than Mark, so Mark must be younger than Kathy."

P.S : I dont see anything which says that joe is older than mark .. ? the statement in the question is - > Mark was born after Joe.

Sujeet Yadav said: (Sep 1, 2011)  
In question it is mentioned that Kathy is older than Joe and it is also mentioned that Mark was born after Joe i.e. Mark is older than Joe but it is nowhere mentioned that Mark is older than Kathy
so answer should be C.

Raaj said: (Sep 16, 2011)  
rewrite as M<J,J<K(assume j get cancel)
therfor M<K
but the given conclusion is K>M
so while shifting M and K
the M<K becomes K>M..

Amit said: (Feb 23, 2012)  
This answer is totally wrong. Answers is C as according to 2nd statement is "Mark was born after Joe" but how many years after? Is it after birth of Kathy or before it, is not provided.

Ritesh. said: (May 20, 2012)  
Hi I agree with the answer. Cause it is said that.
Suppose (joe=j, kathy=k, mark= m).

1. J<k.
2. K>m i.e.m<k.

Hence answer is = true.

Manas said: (Aug 25, 2013)  
As Per my understanding answer should be C because it is explained that Kathy and mark are older than joe but their relationship is not been told that K and M who is older.

Ovi said: (Jan 15, 2014)  
@Ritesh, I have no clue where you got this answer from. You are correct when you say TRUE, but you explain it totally wrong.

The third line needs to be proved and it is not part of the statement so there is no direct K > M as your second point.

- Imagine a straight line and we put Joe as 0 (zero). To the left is the past and to the right is the future.

- Joe is younger than Kathy, meaning Kathy is older than Joe therefore Kathy goes to the LEFT of the line. For Joe to be younger than somebody else he needs to be born AFTER that person and not before.

- Mark was born after Joe, which makes Mark YOUNGER than Joe and then Mark goes to the right of the line.

- Therefore Joe has Kathy to the left and Mark to the right on the axis of time.

- The answer is TRUE.

Joe younger than Kathy and Mark younger than Joe, the line looks like this:

Kathy > Joe > Mark.

Thank You.

Phd said: (Apr 29, 2014)  

This is a partial order and not a complete order. Therefore the correct answer is "uncertain". Please take a course in kindergarten logic.

Pakki said: (Aug 28, 2014)  
People failed to understand the basic inequality.

It is clearly mentioned that "Mark was born after Joe".
It for sure that M>J.

Since there are two possibilities that M>K or M<K.

Si guess situation is uncertain so as to who among Mark and Kathy is elder n to whom.

Pakki said: (Aug 28, 2014)  
Sorry for the wrong interpretation I made earlier.

"Mark was born after Joe".
Implies J>M.

Its simple now,

So its true.
Option A.

Deano said: (Sep 24, 2014)  
The third statement is determined based on the first two statements.

There is an assumption made if the statements are in order of a "timeline" and therefore should be discounted.

BEFORE considering the third statement you can determine that Mark > Kathy OR Mark < Kathy OR Mark = Kathy (i.e. born the same day), which would make the only possible answer as UNCERTAIN.

Adarsh Khamitkar said: (Oct 5, 2014)  
I'm really sorry for my wrong assumption guys!

Here is the trick,
1. K>J
2. j>m

So Kathy has to be older than mark !
Option A is right !

Ak47 said: (Dec 8, 2014)  
Answer is A. The bits that's confusing is the use of after in the sentence. Mark was born after Joe meaning he is younger than Joe.

Shekhar Sharma said: (Jan 31, 2015)  
I can't understand how option A is right answer? Please explain.

Mark said: (Mar 12, 2015)  
Hi @Shekhar, I thought also that C is right, however, I draw a timeline when they were born and you will see it clearly.

First statement: Joe is younger than Katy.

Example: Joe was born in 1980, Kathy in 1970, therefore Joe is 35 today, Kathy is 45.

Second statement: Mark was born AFTER Joe.

Example: Mark has to be born 1980+, lets take 1990, so he is only 25.

Third statement: Kathy is older than Mark.

Example: Based on our ageing Kathy is 45 and Mark is 25, therefore Kathy is older = TRUE A.

Hope it is correct and helpful!

Nate said: (Mar 26, 2015)  
The answer is C.

There is no statement the determines that Mark is younger or older than Kathy. It simply says "mark was born after Joe" there for Mark could be born either between the dates of Kathy and Joe or after the date Kathy was born. Thus showing that the answer is (C) uncertain.

Romel Lacida said: (Apr 25, 2015)  
The answer is true. The 1st and 2nd statements are showing different degree of trueness of its statements. And the 3rd is also a signifying a different meaning.

We should not be bothered of what's being raise in the 1st and second. So the statement Kathy is older than mark connotes different degree, ergo it is true.

Dhaval said: (May 20, 2015)  
Its very simple.

Joe is younger than kathy, so k > j.

It means kathy is older than joe. Mark was born after joe.

j > m.

It means joe is older than mark.

So formulation would be: k > J > M.

So answer is {A} and third given statement is true.

Ram said: (Jul 8, 2015)  
The answer should be C. Although Mark is born after Joe, one cannot interpret if he was born before or after Kathy which means the answer cannot be determined. Hence, uncertain.

Iqra said: (Jul 10, 2015)  
Answer is C. We are not certain about Kathy and Joe here.

Giry said: (Aug 4, 2015)  
The answer is C (uncertain). It is very simple logic.

Luke said: (Aug 20, 2015)  
I thought the answer was C too but that is WRONG. Use a timeline. The left side of the timeline is earlier in time, the right side of the timeline is Present time. Kathy was born before Joe, so she is older. Put the initial K (for Kathy) to the LEFT of J (for Joe).

Now, Mark was born after Joe, so he is younger than Joe - closer to Present, so you need to put M (for Mark) to the right of Joe. You can now see that Kathy is older than Joe and Joe is older than Mark. So Kathy is older than Mark. Oh well, but I'm wiser now. The trick is to think in terms of time (past to present) and NOT less to more.

Dibya said: (Sep 24, 2015)  
The answer is incorrect. Option C is the correct one.

Jay said: (Sep 25, 2015)  
Forum members, answer C is the only correct answer as when we say someone is born *after* someone else, we do not know how far afterward.

If you meant *immediately after*, then you would have to use the word immediately to make any other possibility other than answer C a possibility.

But, even then, maybe Kathy was also born *immediately* after Joe, just more immediately than Mark see?

Hitesh said: (Jan 14, 2016)  
Its so simple, the use of phrase "born after" is what makes it bit confusing. If you say "X is born after Y", it makes Y older than X as Y is born before X.

Ravi said: (Mar 19, 2016)  
If there is anyone who is having confusion regarding correct answer is "Uncertain" or not, here's an explanation.

1. Joe is younger than Kathy i.e. K's age > J's age.
2. Mark was born after Joe i.e. M's age < J's age or J > M.
So, K > J > M.

Thus, A. True is correct answer.

Harini said: (Apr 22, 2016)  
Kathy might born between Joe and Mark. How can you say it is true?

It is 100% UNCERTAIN.

Adam said: (May 4, 2016)  
The second line says Mark was BORN AFTER Joe, meaning Mark is younger than Joe.

So M < J < K.

So, the answer is True.

Param said: (Aug 22, 2016)  
The correct answer is C.

Abhishek said: (Dec 25, 2016)  

1st statement(k>j).

Second statement mark was born after joe that means joe is already there its mark who just arrived so(m<j or j>m).

Third statement(k>m).
Yes because joe is in b/w mark and kathy on the extreme right(m<j<k) so the answer is true.

Robins said: (May 5, 2017)  
Younger means smaller, and born after means smaller.

Joe < kathy.
Mark < Joe.
Mark < Joe < kathy.
So, Kathy is older than mark.

Karthik said: (Oct 27, 2017)  
Hello Friends,

The answer is correct.
1st sentence says J is younger than K, everyone got that right.
But 2nd sentence says Mark was born after Joe. So Mark is younger than Joe.
That makes Mark the youngest.
So Kathy is older than mark is True.

If you put in simple words. Assume you are Joe and you have elder sis Kathy. If the mark is born now he will normally become younger brother for both J and K.

I hope this clears everyone's doubt and confusions.

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