LOGICAL DEDUCTIONS

In order to solve questions related to Logical Puzzle, follow below steps:

Step 1: Note all the observations from the given question.

Step 2: Analyse the observations one by one.

Step 3: Eliminate the impossible options for each observations.

Step 4: Continue this process until three options are eliminated so that only one correct option is left.

Note: There may be some observations, which are irrelevant or not related with respect to the given question. Just ignore such observations.

Seating Arrangements:

Example 1: Five persons - P, Q, R, S and T are standing in a queue.

There are two persons between S and T.

Q is standing in front of T.

R is at the end of the queue.

P is standing immediately behind S.

Who is standing at the middle of the queue?

(1) P (2) Q

(3) S (4) T

It is given that P is standing immediately behind S.(1)

So:

S

P

There are two persons between S and T. ... (2)

Therefore, it has to be either:

It is also given that R is at the end of queue. ... (3)

Combining the above three conditions: SPQTR is the sequence

So, Q is at the middle of the queue.

Answer: (2)

Example 2: A, B, C, D, E and F are three couples sitting around a round table.

D is to the right of A and B is to the left of C.

F - D and B - E are two pairs of person sitting opposite each other.

Who is sitting to the left of F?

(1) A (2) B

(3) C (4) E

D is to the right of A and F and D are sitting opposite each other.

From this we get :

B is to the left of C.

So, they have to occupy the two free position adjacent to each other.

E will occupy the remaining position.

The final arrangement is as follows :

Therefore , C is to the left of F

Answer: (3)

Blood Relations:

Example 3: Introducing a boy, a girl said, "He is the son of the daughter of the father of my uncle." How is the boy related to the girl?

(1) Brother (2) Nephew

(3) Uncle (4) Son in law

The father of the boy's uncle -> the grandfather of the boy and daughter of the grandfather -> sister of father

Answer (1)

Example 4: Pointing towards a man is the photograph, lady said "the father of his brother is the only son of my mother". How is the man related to day?

(1) Bother (2) Son

(3) Cousin (4) Nephew

The father of this brother means "his father"" is the only son of my mother means "my brother".

It means lady is the father's sister of the man's father.

Answer: (4)

Example 5: Soni, who is Dubey's daughter, says to Preeti, "Your mother Shyama is the youngest sister of my father, Dubey's Father third child is Prabhat". How is Prabhat related to Preeti ?

(1) Uncle (2) Father

(3) grandmother (4) Father in law

Preeti's mother shyama is youngest sister of Dubey & sister of Prabhat.

Therefore Prabhat Preeti's uncle.

Answer: 1

Puzzles:

Example 6: Read the following information and answer the questions:

There are five men A, B, C, D and E and six women P, Q, R, S, T and U.

A, B and R are advocates; C, D, P, Q and S are doctors and the rest are teachers.

Some teams are to be selected from amongst these eleven persons subject to the following conditions:

A, P and U have to be together.

B cannot go with D or R.

E and Q have to be together

C and T have to be together.

D and P cannot go together.

C cannot go with Q.

If the team is to consist of two male advocates, two lady doctors and one teacher, the members of the team are:

(1) A B P Q U (2) A B P U S

(3) A P R S U (4) B E Q R S

The made advocates are A and B, lady doctors are P, Q and S; Teachers are E, T and U.

Now A and B will be selected/ A, P and U have to be together.

Now, we have to select one lady doctor more.

It can be Q or S. But Q and E have to be together.

Since E is not selected, so S will be selected.

Thus, the team is A B P U S.

Answer: (2)

Example 7: Mohini, Nanda, Seema, Anisha and Sangeeta are participating in a race. At the end of the race, Seema was ahead of Nanda but behind Anisha. Mohini was behind of all. Sangeeta was ahead of Seema. Who must be the first three in order of finishing the race?

(1) Mohini, Sangeeta, Seema

(2) Sangeeta, Seema, Anisha

(3) Anisha, Sangeeta, Seema

(4) Seema, Sangeeta, Anisha

From the first condition, the order is Nanda Seema Anisha.

From the second condition, the order is Mohini Nanda Seema Anisha.

From the third condition, the order is Mohini Nanda Seema Sangeeta Anisha.

So, the first three that finish the race are Seema Sangeeta Anisha.

Answer (4)

Example 8: A murder was committed. In response, the police rounded up five suspects, Amar, Boby, Chintan, Dushyant, and Ela and took them in for questioning.

The five suspects gave the following statements:

Amar: Boby didn't do it.

Boby: Chintan didn't do it.

Chintan: Ernie didn't do it.

Dushyant: I didn't do it.

Ela: Either Amar or Chintan did it.

It turned out that exactly one of the suspects committed the murder, and it turned out that exactly four of the suspects told the truth and one lied. Who committed the murder?

(1) Amar (2) Boby

(3) Chintan (4) Dushyant

We could work backwards to solve this one.

Set up a table and, for each possible murderer, set up a table listing whether each statement is true or false:

The only way there can be four true statements is if Chintan committed the murder.

Therefore, he must be the murderer.

Answer: 3

Example 9: Hari (H), Gita (G), Irfan (I) and Saira (S) are siblings (i.e. brothers and sisters).

All were born on 1st January.

The age difference between any two successive siblings (that is born one after another) is less than3 years.

Given the following facts:

(1) Hari's age + Gita's age > Irfan's age + Saira's age.

(2) The age difference between Gita and Saira is 1 year. However, Gita is not the oldest and Saira is not the youngest.

(3) There are no twins.

In what order were they born (oldest first)?

(1)HSIG (2)SGHI

(3)IGSH (4)IHSG

Let us Hari's age is H, Gita's age is G, Saira's age is S, Irfan age is I.

From statement (1): H + G >I+ S

From statement (2): Either S - G = 1 or G - S = 1

From statement (3): No twins.

Now analyse each options:

Option (1): HSIG not possible because G and S must be lie together because there age difference is exact one year.

Option (2): SGHI is a possible order

Option (3): IGSH not possible because H + G >I+ S.

From IGSH option we get I+ S > G + H So, both contradict each other.

Option (4): IHSG from here I > H, S > G, thus I + S > H + G which contradict statement (1)

Answer: 2

Example 10:

Abhishek is elder to Savar

Savar is younger to Anshul

Which of the given conclusion is logically valid and is inferred from the above statements?

(1) Abhishek is elder to Anshul

(2) Anshul is elder to Abhishek

(3) Abhishek and Anshul are of the same age

(4) No conclusion follows

Savar < Abhishek

Savar < Anshul No conclusion because there are no direct relation between Abhishek and Anshul.

Answer is (4)

Example 11: Amar, Akbar and Antony are 3 friends, one of whom is a doctor, another is an engineer and the third is a professor.

Amar is not an engineer. Akbar is the shortest.

The tallest person is a doctor.

The engineer's height is the geometric mean of the heights of the other two.

Then which of the following is true?

(1) Amar is a doctor and he is the tallest

(2) Akbar is a professor and he is the tallest

(3) Antony is a doctor and he is the shortest

(4) Antony is a doctor and he is the tallest

Analyse each statement. Easiest way to solve this is to represent data in tabular format.

Statement 1: Amar is not an engineer

Statement 2: Akbar is the shortest

Statement 3: The tallest person is a doctor

Statement 4: The engineer's height is the geometric mean of the heights of the other two.

This means that engineer height is middle.

So if Doctor is tallest and Engineer is middle height, then we can conclude that Professor is shortest.

From this we can conclude that Akbar is Professor since Statement 2 says that Akbar is Shortest.

If Akbar is Professor then he cannot be Doctor or Engineer.

In above table, for Engineer only option left is Anthony because Akbar is Professor and Statement 1 mentions that Amar is not Engineer.

So Amar is Doctor as Akbar is Professor and Anthony is Engineer.

Answer: 1

Example 12: In each of the following groups of words is a hidden number, based on which you should arrange them in ascending order. Pick the right answer:

A. Tinsel event

B. Man in England

C. Good height

D. Last encounter

1. A, B, C, D 2. C, B, D, A

3. A, C, D, B 4. C, D, B, A

On observing the given group of words, we can find the hidden number as below:

A. Tinsel event .................... 11

B. Man in England .................... 9

C. Good height .................... 8

D. Last encounter .................... 10

On arranging above numbers in ascending order:

8, 9, 10, 11

I.e. C, B, D, A

Answer: 2

Example 3:

L is the tallest and eldest of a group of five people K, L, M, N and P.

M is elder to N and shorter than K.

M and P are of same age and P is taller than K.

N and K are of same height and K is younger to P.

Which of the following inferences is certain?

1. P is taller than M

2. N is the youngest

3. N is elder to P

4. N is elder to K

Analyse each of the statement.

Statement 1: L is the tallest and eldest of a group

Statement 2: M is elder to N and shorter than K

Statement 3: M and P are of same age and P is taller than K

Statement 4: N and K are of same height and K is younger to P

So it can be concluded that P is taller than M.

Answer: 1