In the particular year 12th January is a Sunday
In the particular year 12th January is a Sunday, then which one of the following is correct?
- 15th July is a Sunday if the year is a leap year.
- 15th July is a Sunday if the year is not a leap year.
- 12th July is Sunday if the year is a leap year.
- 12th July is a not Sunday if the year is a leap year.
Answer: C
Explanation
Method I:
12th January is Sunday. If it is not a leap year, then:
Days between 15th July and 12th January = (31 - 11) + 28 + 31 + 30 + 31 + 30 + 14 = 184
Odd days = Remainder (184/7) = 2
So, day on 15th July if that year is a non-leap year = Sunday + 2 = Tuesday
If it was a leap year, then we need to take into account one extra day in the month of February, i.e. 29th February.
So, day on 15th July if that year is a leap year = Sunday + 3 = Wednesday
Similarly, the day on 12th July (non-leap year) = Day on 15th July - 3 = Tuesday - 3 = Saturday
The day on 12th July (leap year) = Day on 15th July - 3 = Wednesday - 3 = Sunday
Method II:
Just count the odd days.
Odd days in January = Remainder [(31 - 11)/7] = Remainder (20/7) = 6
Odd days in February = 0 (if non-leap year), 1 (if leap year)
Odd days in March = 3
Odd days in April = 2
Odd days in May = 3
Odd days in June = 2
So, number of odd days till June end in a non-leap year = 6 + 0 + 3 + 2 + 3 + 2 = 16 = 2
So, number of odd days till June end in a leap year = 6 + 1 + 3 + 2 + 3 + 2 = 17 = 3
July 12 means 11/7, i.e. 4 more odd days.
July 15 means 14/7, i.e. 0 more odd days.
So, day on July 12th (non-leap year): Sunday + 2 + 4 = Saturday
And, day on July 12th (leap year): Sunday + 3 + 4 = Sunday
- Exam Year: 2020