Aptitude : Calender

(11) It was Sunday on Jan 1, 2000. What was the day of the week on Jan 1, 2005?

• (a)Tuesday
• (b)Wednesday
• (c)Monday
• (d)Sunday

Answer

Correct Answer : (d) Sunday
January 1, 2000 is a Sunday.
The years from 2000 to 2005 consist of 5 years. Among them, 2000 and 2004 are leap years (since they are divisible by 4), and 2001, 2002, and 2003 are ordinary years.
An ordinary year has 1 odd day, and a leap year has 2 odd days.
So, in this case, there are 2 leap years contributing 4 odd days and 3 ordinary years contributing 3 odd days, making a total of 7 odd days.
7 odd days means a full week, which does not change the day of the week.
Therefore, the day of the week on January 1, 2005 was also Sunday.

(12) What was the day of the week on 15th August, 1947?

• (a)Friday
• (b)Wednesday
• (c)Monday
• (d)Saturday

Answer

Correct Answer : (a) Friday
First, let’s break down the years from 1900 to 1947:
There are 47 years in total. Out of these, we need to calculate the number of leap years and common years. A leap year is divisible by 4, so the potential leap years here are 1904, 1908, …, 1944. However, 1900 is not a leap year because although it’s divisible by 4, century years are only leap years if they are divisible by 400, which 1900 is not. Therefore, there are 12 leap years and 35 common years.
A leap year has 2 odd days and a common year has 1 odd day. Therefore, the total number of odd days from the years is 122 + 351 = 59 odd days.
Next, let’s calculate the odd days for 1947 up to August 15:
In 1947, up to August 15, the months break down as follows: January has 31 days (3 odd days), February has 28 days (0 odd days), March has 31 days (3 odd days), April has 30 days (2 odd days), May has 31 days (3 odd days), June has 30 days (2 odd days), July has 31 days (3 odd days), and August has 15 days (1 odd day). Therefore, the total number of odd days from these months is 3 + 0 + 3 + 2 + 3 + 2 + 3 + 1 = 17 odd days.
The total number of odd days from January 1, 1900 to August 15, 1947 is therefore 59 (from the years) + 17 (from the months in 1947) = 76 odd days.
Dividing 76 by 7 (the number of days in a week) gives us a remainder of 6. Starting from Monday (our reference point), if we count forward by 6 days, we land on Friday.
Therefore, the day of the week on August 15, 1947 was Friday.

(13) If 26th January, 2020 is Sunday, what was the day of the week on 26th January, 2019?

• (a)Tuesday
• (b)Saturday
• (c)Monday
• (d)Wednesday

Answer

Correct Answer : (b) Saturday
To calculate this, you would subtract the necessary days and adjust for the seven-day week. If January 26, 2020 is a Sunday, then January 26, 2019 would be one day before the corresponding day in the next year.
Since there’s no leap year involved between January 26, 2019, and January 26, 2020, it’s exactly 365 days, which is 52 weeks and 1 day. So, you simply go back one day from Sunday.
Therefore, January 26, 2019 was a Saturday.

(14) On 11th November, 2015 it was Wednesday. What was the day of the week on 11th November, 2014?

• (a)Wednesday
• (b)Sunday
• (c)Monday
• (d)Tuesday

Answer

Correct Answer : (d) Tuesday
Going back from Nov 11, 2015 to Nov 11, 2014, there are no leap years, so it’s exactly 365 days. This is 52 weeks and 1 day, which is 1 day before Wednesday, so the day was Tuesday.

(15) On 5th May, 2018 Saturday falls. What day of the week was it on 5th May, 2017?

• (a)Tuesday
• (b)Saturday
• (c)Friday
• (d)Wednesday

Answer

Correct Answer : (c) Friday
Going back from May 5, 2018 to May 5, 2017, there are no leap years, so it’s exactly 365 days. This is 52 weeks and 1 day, which is 1 day before Saturday, so the day was Friday.