What comes at X and Y respectively in the following sequence ? January, January, December, October, X, March, October, Y, September
- (a) July, May
- (b) July, April ✓ UPSC's answer
- (c) June, May
- (d) June, April
Why the answer is (b)
• Write each month as its number in the year: January = 1, December = 12, October = 10, March = 3, September = 9.
• Moving forward through the calendar, the gaps are 12, 11, 10, 9, 8, 7, 6, 5 months: January + 12 = January, January + 11 = December, December + 10 = October.
• October + 9 months = July, so X = July; July + 8 months = March, which matches the next term.
• March + 7 = October (matches); October + 6 months = April, so Y = April; April + 5 = September (matches).
• So X = July and Y = April, option (b).
Why the other options are wrong
- (a) July, May
- Y = May breaks the pattern: the gap after October is 6 months, which lands on April; May + 5 months would give October, not September.
- (c) June, May
- X = June breaks the pattern: October + 9 months is July, and June + 8 months would give February, not March.
- (d) June, April
- X = June breaks the pattern: October + 9 months is July, and June + 8 months would give February, not March.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2025, held on 25 May 2025. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.