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Eight people – A, B, C, D, E, F, G and H are sitting around a circular table facing the centre, but not necessarily in the same order. All of them are at equidistant. Each one of them teaches different subjects viz., English, Hindi, Mathematics, Biology, Psychology, Physics, Chemistry and Accounts, but not necessarily in the same order.

 The person who teaches Accounts, sits third to the right of G. C is an immediate neighbour of G. The person who teaches Mathematics sits second to the left of C. B sits third to the right of H. H teaches neither Accounts nor Mathematics. Only two persons sit between C and the person who teaches Physics. A and F are immediate neighbours of each other. Neither A nor F teaches Accounts. The person who teaches English sits second to the right of A. Two persons sit between D and the person who teaches Hindi. D does not teach Accounts. The person who teaches Psychology is an immediate neighbour of the person who teaches Accounts. The person who teaches Physics sits second to the left of A. One of the immediate neighbours of G teaches Chemistry.

 1. Who among the following teaches Chemistry?
 (1) A
 (2) H
 (3) D
 (4) G
 (5) None of these
in Numerical Ability by Veteran (431k points) | 771 views
0
I think answer is none of the above or cannot be determined is the best correct option. If someone asks who does teach chemistry. and, if you answer H. It means you are also saying at the same time that H only teaches chemistry. No body else teaches chemistry . but it is wrong B OR C may also teach chemistry.

moreover, each people teaches only one unique subject as given in the question.

3 Answers

+2 votes
Best answer

A B C D E F G

We have eight people and eight seats around a round table, so a person has two neighbours. Just writing the given conditions: '-' shows a place taken by a undecided person. (Accounts) means the person teaching Accounts.

1. G _ _ (Accounts)
2. G C or C G
3. (Maths) _ C
4. H _ _ B
5. H no Accounts no Maths
6. C _ _  (Physics) or (Physics) _ _ C
7. A F or F A - both not Accounts
8. A _ (English)
9. D _ _ (Hindi) or (Hindi) _ _ D  D not Accounts
10. (Accounts) (Psychology) or (Psychology) (Accounts)
11. (Physics) _ A
12. G (Chemistry) or (Chemistry) G

First seeing Accounts- it is not taught by G or C or H or A or F or D. So either B or E. But seeing the conditions 1 and 4, B cannot be Accounts as G != H. So, Accounts must be taught by E - condition 13. 

So,
G _ _ E
E is teaching Accounts

Now A F cannot go in the two missing places above as
G A F E would mean G A F E H _ _ B, making A and B (or F and B) the neighbors of G, but C must be a neighbor of G as per question.

So, E is teaching Accounts and AF cannot be between G and E. Also, an interesting condition is given in conditions 6 and 11 because it says either C _ _ _ _ A or A C. Now lets see the possibilities for placing H _ _ B by trying to place H in all possible places.

Case 1: G H _ E B _ _ _ but we have C neighbor of G, so, we get 
G H _ E B _ _ C -After C the fifth place is taken by B. So, A C must be there. Thus, we get
G H D E B F A C as Case 1.

Case 2: G _ H E _ B _ _ only place for A F is at the end and C is a neighbor of G. So, this case leads to G C H E D B A F (again using C _ _ _ _ A).

Case 3: G _ _ E H _ _ B - again we can place C and AF giving G C D E H F A B as case 3.

Case 4: G B _ E _ _ H _ - again we can place C and AF giving G B D E A F H C as case 4.

Case 5: G _ B E _ _ _ H - again we can place C and AF giving G C B E D F A H as case 5. 

So, lets assign the subjects in each case:

Condition No. Case 1
G H D E B F A C
Case 2
G C H E D B A F
Case 3
G C D E H F A B
Case 4
G B D E A F H C
Case 5
G C B E D F A H
13 E- Accounts E - Accounts E - Accounts E - Accounts E - Accounts
8 G - English G - English G - English H - English G - English
11 B - Physics D - Physics H - Physics D - Physics D - Physics
3 F - Maths F - Maths B - Maths F - Maths H - Maths violates 5
9 C - Hindi C - Hindi violates 12 F - Hindi C - Hindi  
10 D - Psychology   D - Psychology A - Psychology  
12 H - Chemistry   C - Chemistry B - Chemistry  
  A - Biology   A - Biology G - Biology  

So, there are 3 possibilities for Chemistry- H, C or B. So, answer must be None of these. 

by Veteran (431k points)
selected by
+1 vote
Answer : (2) H

G-English,H-Chemistry,D-Psychology,E-Accounts,B-Physics,F-Math,A-Bio,C-Hindi (anti clockwise)

This satisfy all the given conditions in this question.
by (25 points)
0
why not C or B? All 3 satisfy all the requirements.
0
just followed trail and error method based on second statement that c is immediate neighbour of g. From here you can derive the answer. Also it is very easy to find that E teaches accounts by eliminating each member based on given conditions.

why your answer is not right? Well for that I would have to go through you explanation which contains 2 paragraphs and one gigantic table. Sorry don't have enough time for that.
0
No need. But you can just substitute C or B too. They are also correct.
0 votes
A-Bio

B-Math

C-Che

D-Psycholoy

E-Accounts

F-Hindi

G- Eng

H-Physics

C is the immediate neighbour og G  who teaches chemistry. You can get this if  you check the above conditions with the following sequence.

And the order is- H-E-D-C-G-B-A-F-H in clock wise direction. So answer is C.
by (109 points)
0
It can be H, C or B.
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