Passage

Directions for the following 6 (six) items : Read the information given below and answer the six items that follow. A, B, C and D are students. They are studying in four different cities, viz., P, Q, R and S (not necessarily in that order). They are studying in Science college, Arts college, Commerce college and Engineering college (not necessarily in that order), which are situated in four different States, viz., Gujarat, Rajasthan, Assam and Kerala (not necessarily in that order). Further, it is given that— (i) D is studying in Assam (ii) Arts college is located in city S which is in Rajasthan (iii) A is studying in Commerce college (iv) B is studying in city Q (v) Science college is located in Kerala

Which one of the following statements is correct regarding Engineering college?

(a) C is studying there.
(b) B is studying there.
(c) It is located in Gujarat.
(d) D is studying there. ✓ UPSC's answer

Why the answer is (d)

• From constraint (ii), Arts college is in city S, Rajasthan; from (v), Science college is in Kerala. This leaves Commerce and Engineering to be placed in Gujarat and Assam.

• Constraint (i) states D is studying in Assam, so D's college must be the one located in Assam. Constraint (iii) states A is in Commerce. If Commerce were in Assam, both A and D would be in Assam, which is impossible since each student occupies a different city and state. Therefore Commerce is in Gujarat and Engineering is in Assam.

• Since Engineering is in Assam and D is in Assam, D is studying in Engineering college.

• B is in city Q (constraint iv). Arts is in city S, so B cannot be in Arts. B is not A (Commerce) or D (Engineering), so B must be in Science (Kerala, city Q).

• By elimination, C is in Arts college (city S, Rajasthan), and A is in Commerce college (Gujarat, city P or R).

• The question asks what is correct regarding Engineering college: D is studying there, which matches option (d).

Why the other options are wrong

(a) C is studying there.: C is studying in Arts college (city S, Rajasthan), not Engineering. C is the only student left after assigning A to Commerce, B to Science, and D to Engineering.
(b) B is studying there.: B is studying in Science college in Kerala (city Q), not Engineering. B cannot be in Arts because Arts is in city S while B is in city Q, and B is neither A (Commerce) nor D (Engineering).
(c) It is located in Gujarat.: Engineering college is located in Assam, not Gujarat. Commerce is the college in Gujarat, as shown by the elimination that Commerce cannot be in Assam (where D already is) and therefore must be in Gujarat, leaving Engineering for Assam.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2018, held on 3 June 2018. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.