If July 3rd, 1983 was a Sunday, then what day of the week was October 11th, 1983?

To determine the day of the week for October 11th, 1983, given that July 3rd, 1983, was a Sunday, we can follow these steps:

1. Break Down the Problem

• Determine the number of days between July 3rd and October 11th, 1983.
• Calculate what day of the week it will be after adding those days to Sunday.

2. Relevant Concepts

• The number of days in each month is essential for this calculation.
• Days in the months:
  • July: 31 days (from July 3rd to July 31st: 28 days)
  • August: 31 days
  • September: 30 days
  • October: 11 days

3. Analysis and Detail

• Calculate the total number of days:
  • From July 3rd to July 31st: $31 - 3 = 28$ days
  • Full month of August: $31$ days
  • Full month of September: $30$ days
  • From October 1st to October 11th: $11$ days

Calculating the total: $28 \text{ (July)} + 31 \text{ (August)} + 30 \text{ (September)} + 11 \text{ (October)} = 100 \text{ days}$

4. Verify and Summarize

• To find the day of the week, divide the total number of days by 7: $100 \div 7 = 14 \quad \text{(remainder 2)}$ The remainder means we count 2 days from Sunday (July 3rd).

From Sunday:

• 1 day later: Monday
• 2 days later: Tuesday

Final Answer

October 11th, 1983, was a Tuesday.