29th February of the year 2000 was Tuesday. After this date how many times 29th February falls on Tuesday in the whole century ?
[amp_mcq option1=”3″ option2=”4″ option3=”5″ option4=”6″ correct=”option1″]
This question was previously asked in
UPSC CAPF – 2015
Feb 29, 2000 was a Tuesday.
Leap years after 2000 in that century are 2004, 2008, …, 2096.
The day shifts by 5 days (3 normal years + 1 leap year = 365*3 + 366 = 1461 days; 1461 mod 7 = 5) every 4 years.
Starting from Tuesday (in 2000, reference):
2004: Tuesday + 5 days = Sunday
2008: Sunday + 5 days = Friday
2012: Friday + 5 days = Wednesday
2016: Wednesday + 5 days = Monday
2020: Monday + 5 days = Saturday
2024: Saturday + 5 days = Thursday
2028: Thursday + 5 days = Tuesday (1st occurrence after 2000)
The cycle of days for Feb 29 is Tuesday, Sunday, Friday, Wednesday, Monday, Saturday, Thursday, Tuesday…
This repeats every 7 leap years, which is 28 years.
The leap years after 2000 where Feb 29 is Tuesday will be 2000 + 28n.
For n=1: 2000 + 28 = 2028.
For n=2: 2000 + 56 = 2056.
For n=3: 2000 + 84 = 2084.
For n=4: 2000 + 112 = 2112 (outside the century 2001-2100 or 2001-2099).
Thus, Feb 29 falls on Tuesday after 2000 in the years 2028, 2056, and 2084. This is a total of 3 times.