2019 CSAT, all questions
UPSC Prelims 2019 · CSAT
Question 59: Logical Reasoning and Mental Ability
Which year has the same calendar as that of 2009 ?
a2018
b2017
c2016
d2015
AnswerUPSC’s answer is (d).
A non-leap year repeats a calendar when the day shift is a multiple of 7. From 2009 to 2015, six years (2009 to 2014) pass, including leap year 2012: 6 × 365 + 1 = 2191 days = 313 weeks exactly. So 2015 begins on the same weekday as 2009, and both are non-leap. 2016 is a leap year, and 2017 and 2018 begin on different weekdays.
Why each option is right or wrong
- (a) Wrong: 2018 begins four weekdays later.
- (b) Wrong: 2017 begins three weekdays later.
- (c) Wrong: 2016 is a leap year, so its calendar cannot match a non-leap year.
- (d) Right: 2191 days is a whole number of weeks.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2019, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.