Final answer:
Using Zeller's Congruence algorithm, we find that 13th August 1975 was a Wednesday. This method involves reassigning certain dates and applying them to a specific mathematical formula.
Step-by-step explanation:
To determine the day of the week for a specific date, we will use Zeller's Congruence, an algorithm devised by Christian Zeller to calculate the day of the week for any date. Here are the steps:
First, let's assign values to variables. For example, if we are working with 13th of August, 1975, then day (D) = 13, month (M) = 8, and the year (Y) = 1975.
Considering August as a month, we re-label it as 10 (as per Zeller's Congruence, January and February are treated as months 13 and 14 of the previous year. Hence, the months March to December are re-labelled as 3 to 12). Therefore, revised month (M) = 10.
We also revise the year for January or February to be the previous year, but it's August in our case, so revised year (Y) = 1975.
Then we apply the Zeller's Congruence formula:
F = K + [(13(M+1))/5] + Y + [Y/4] + [C/4] - 2C.
Here, K is the day (13), M is the revised month (10), Y is the last two digits of the revised year (75), and C is the first two digits of the revised year (19).
After inserting these values into the formula, we would then find 'F' modulo 7 which will give us a number between 0 and 6. Consulting a key that assigns numbers to days of the week, where: 0 = Saturday, 1 = Sunday, 2 = Monday, etc., we find that the day on 13th August 1975 was a Wednesday.
Learn more about algorithm