If the first day of a year (other than the leap year) was Friday, then which one of the following was the last day of that year ?<\/p>\n
[amp_mcq option1=”Monday” option2=”Friday” option3=”Saturday” option4=”Sunday” correct=”option2″]<\/p>\n
Let’s rethink.
\nDay 1 is Friday.
\nAfter 7 days (Day 8), it’s Friday again.
\nAfter 364 days (52 weeks), the day is the same as Day 1. So, Day 364 is a Friday.
\nDay 365 is the day after Day 364. So, Day 365 is Saturday. This is also incorrect, as the well-known property is that the first and last days are the same.<\/p>\n
Let’s think about the “extra” day. If the first day of a year (other than the leap year) was Friday, then which one of the following was the last day of that year ? [amp_mcq option1=”Monday” option2=”Friday” option3=”Saturday” option4=”Sunday” correct=”option2″] This question was previously asked in UPSC CISF-AC-EXE – 2018 Download PDFAttempt Online If the first day of a non-leap year … <\/p>\n
\nThe days of the year are Day 1, Day 2, …, Day 365.
\nDay 1 = Friday.
\nDay 2 = Saturday.
\nDay 7 = Thursday.
\nDay 8 = Friday (1 week after Day 1).
\nDay (1 + 7k) is Friday.
\nWe want to find the day for Day 365.
\n365 = 1 + 364.
\nThe number of “extra” days after Day 1 is 364.
\n364 modulo 7 is 0 (364 = 52 * 7).
\nThis means Day 365 is 0 days past Friday in the weekly cycle, counting from Day 1.
\nSo, if Day 1 is Friday, Day (1 + 364) i.e., Day 365, is Friday + 0 days = Friday.
\n<\/section>\n
\nIn a leap year (366 days), the last day would be one day later in the week than the first day.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"