UPSC Prelims 2017 CSAT Paper II · Q70 of 79 Comprehension medium

Passage

Directions for the following 3 (three) items : Consider the given information and answer the three items that follow. A, B, C, D, E, F and G are Lecturers from different cities—Hyderabad, Delhi, Shillong, Kanpur, Chennai, Mumbai and Srinagar (not necessarily in the same order) who participated in a conference. Each one of them is specialized in a different subject, viz., Economics, Commerce, History, Sociology, Geography, Mathematics and Statistics (not necessarily in the same order). Further 1. Lecturer from Kanpur is specialized in Geography 2. Lecturer D is from Shillong 3. Lecturer C from Delhi is specialized in Sociology 4. Lecturer B is specialized in neither History nor Mathematics 5. Lecturer A who is specialized in Economics does not belong to Hyderabad 6. Lecturer F who is specialized in Commerce belongs to Srinagar 7. Lecturer G who is specialized in Statistics belongs to Chennai

To which city does the Lecturer specialized in Economics belong?

  1. (a) Hyderabad
  2. (b) Mumbai ✓ UPSC's answer
  3. (c) Neither Hyderabad nor Mumbai
  4. (d) Cannot be determined as data are inadequate

Why the answer is (b)

• From clues 6 and 7, F is from Srinagar (Commerce) and G is from Chennai (Statistics). From clue 2, D is from Shillong. From clue 3, C is from Delhi (Sociology). This leaves Hyderabad, Kanpur, and Mumbai for A, B, and E.

• Clue 1 states the lecturer from Kanpur specializes in Geography. Clue 5 states A (Economics) is not from Hyderabad. Since A is not from Hyderabad, A must be from either Kanpur or Mumbai. However, A cannot be from Kanpur because the Kanpur lecturer specializes in Geography, not Economics. Therefore, A must be from Mumbai.

• Since A is from Mumbai, the remaining cities for B and E are Hyderabad and Kanpur. The Kanpur lecturer specializes in Geography. Clue 4 states B is specialized in neither History nor Mathematics. The remaining subjects for B and E are History, Mathematics, and Geography (since Economics, Commerce, Sociology, Statistics are taken by A, F, C, G). Wait, let's list subjects: A(Econ), F(Comm), C(Soc), G(Stat). Remaining subjects: History, Math, Geo, Soci? No, C is Soc. Remaining: History, Math, Geo. And one more? Total 7 subjects. A(Econ), F(Comm), C(Soc), G(Stat). Left: History, Math, Geo. And... wait. 7 people. A, B, C, D, E, F, G. Subjects: Econ, Comm, Soc, Stat, Hist, Math, Geo. Assigned: A(Econ), F(Comm), C(Soc), G(Stat). Unassigned subjects: History, Math, Geo. Unassigned people: B, D, E. Cities: A(Mumbai), C(Delhi), D(Shillong), F(Srinagar), G(Chennai). Unassigned cities: Hyderabad, Kanpur. People left for these cities: B, E. D is in Shillong. So B and E are in Hyderabad and Kanpur. Kanpur is Geography. So either B or E is Geography. Clue 4 says B is not History or Math. So B must be Geography (since the only options for B's subject among the remaining are History, Math, Geo, and B can't be H or M). Thus B is from Kanpur (Geography). This leaves E from Hyderabad. E's subject must be one of History or Math. D is from Shillong. D's subject is the last one (History or Math). This confirms A is from Mumbai.

• Therefore, the lecturer specialized in Economics (A) belongs to Mumbai.

Why the other options are wrong

(a) Hyderabad
Lecturer A (Economics) is explicitly stated not to belong to Hyderabad in clue 5.
(c) Neither Hyderabad nor Mumbai
The data is sufficient to determine that A belongs to Mumbai, so it is not 'neither'.
(d) Cannot be determined as data are inadequate
The constraints allow for a unique solution where A is from Mumbai, so the data is adequate.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2017, held on 18 June 2017. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

Reading the answer is not the same as getting it right under a clock. Practise this question with UPSC's negative marking, and anything you miss goes into an error notebook until you get it right twice.

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