2024 CSAT, all questions
UPSC Prelims 2024 · CSAT
Question 38: Logical Reasoning and Mental Ability
The calendar for the year 2025 is same for
a2029
b2030
c2031
d2033
AnswerUPSC’s answer is (c).
A calendar repeats when the odd days since 2025 add up to a multiple of 7. A normal year adds 1 odd day and a leap year adds 2. From 2025 to 2031: 2025, 2026 and 2027 give 1 each, leap 2028 gives 2, and 2029 and 2030 give 1 each: 1 + 1 + 1 + 2 + 1 + 1 = 7. So 1 January 2031 falls on the same weekday as 1 January 2025, and 2031 is not a leap year, so the calendars match.
Why each option is right or wrong
- (a) Wrong. 2029 is four years on, with one leap year: 5 odd days, not a multiple of 7.
- (b) Wrong. 2030 gives 6 odd days (5 + 1), not 7.
- (c) Right. The total is 7 odd days.
- (d) Wrong. 2033 is eight years on with two leap years (2028, 2032): 10 odd days, which leaves 3 over.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2024, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.