ASunday
BTuesday
CThursday
DWednesday
Answer:
C. Thursday
Read Explanation:
Solution:
To determine the day of the week on 6th August 1987, we use the following method:
1987 = 1600 + 300 years (1601 to 1900) + 86 years (1901 to 1986) + year 1987
No. of odd days from 1601 to 1900 = 1 odd day (5 odd days in every 100 years)
The total number of odd days from 1901 to 1986 = 21 leap years + 65 ordinary years = 42 + 65 = 107 odd days = 2 odd days.
In 1600 years, odd days = 0
So total in 1986 years = 0 + 1 + 2 = 3 odd days
Month (1987) | No. of odd days = no. of days in the month (mod 7) |
January | 3 |
February | 0 (not a leap year) |
March | 3 |
April | 2 |
May | 3 |
June | 2 |
July | 3 |
In 1987, the no. of days up to 6 August = 31(Jan) + 28 (Feb) + 31(Mar) + 30(Apr) + 31(May) + 30(June) + 31(July) + 6 days (Aug) = 218/7 = 1 odd days.
Therefore, total no. of odd days up to 6th August 1987 = 3 + 1 = 4
Now, if the remainder (the total no. of odd days) is as follows, then it corresponds to the following day:
No. of odd days | Day |
0 | Sunday |
1 | Monday |
2 | Tuesday |
3 | Wednesday |
4 | Thursday |
5 | Friday |
6 | Saturday |
We have remainder 4 which corresponds to Thursday.
Hence, on 6th August 1987, it was a Thursday.