2020 CSAT, all questions

UPSC Prelims 2020 · CSAT

Question 48: Logical Reasoning and Mental Ability

The letters from A to Z are numbered from 1 to 26 respectively. If GHI = 1578 and DEF = 912, then what is ABC equal to?

a492
b468
c262
d246

AnswerUPSC’s answer is (d).

Replace letters by their positions: DEF = 456 and GHI = 789. The given codes are 912 = 2 × 456 and 1578 = 2 × 789, so the code is the three-digit number made by joining the positions, doubled. ABC = 123, and 2 × 123 = 246.

Why each option is right or wrong
  • (a) 492 would be 4 × 123.
  • (b) 468 would be 2 × 234, the code for BCD.
  • (c) 262 does not follow the doubling rule.
  • (d) Right: 2 × 123 = 246.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2020, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.