The calendar for the year 2009 was the same as that of the year _______.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 2015
Two years have the same calendar when they are of the same kind (both ordinary or both leap) and the days between their 1 January make whole weeks. An ordinary year has 365 days = 52 weeks + 1 day, so it moves the starting day on by 1 odd day; a leap year moves it on by 2 odd days. 2009 is an ordinary year.
Odd days, year by year from 2009:
2009: 1, 2010: 1, 2011: 1, 2012 (leap): 2, 2013: 1, 2014: 1
Total \(=1+1+1+2+1+1=7\) odd days \(=\) one whole week
So 1 January 2015 falls on the same day as 1 January 2009, and 2015 is also an ordinary year.