The second day of a 31-day month is a Sunday. The following month also has 31 days. What day of the week will be the last day of that next month?

Introduction / Context:
This calendar question asks you to reason about two consecutive 31-day months. You are given the weekday of the second day of the first month and asked to find the weekday of the last day of the second month. This tests your ability to track weekday shifts across multiple months of known length.

Given Data / Assumptions:

• The first month has 31 days.
• The second day of this month is Sunday.
• The following month also has 31 days.
• We must find the weekday of the last (31st) day of the second month.

Concept / Approach:
We use two ideas:

• Within a month, the weekday moves forward by 1 each day.
• Across a full 31-day month, the weekday of the next month's 1st day is shifted by 3 days, because 31 = 28 + 3 and 28 days form exactly 4 weeks.

We anchor everything to the known information that the second day of the first month is Sunday and then work forward month by month.

Step-by-Step Solution:
Step 1: The second day of the first month is Sunday. Therefore, the first day of that month is Saturday.Step 2: The first month has 31 days. To find the weekday of the 31st of this month, move 30 days forward from the 1st.Step 3: Since 30 = 28 + 2, the weekday shifts 2 days ahead from the weekday of the 1st.Step 4: Starting from Saturday (the 1st), two days forward gives Monday. So the 31st day of the first month is Monday.Step 5: The next month starts the day after the 31st of the first month. So the 1st day of the second month is Tuesday.Step 6: The second month also has 31 days. The 31st day of the second month is 30 days after its 1st day.Step 7: Again, 30 days correspond to 28 + 2 days, so the weekday shifts 2 days ahead from Tuesday.Step 8: Moving 2 days forward from Tuesday gives Thursday.

Verification / Alternative check:
You can reason more compactly: a 31-day month advances the weekday of the same date next month by 3 days. Two consecutive 31-day months therefore advance the weekday by 6 days for the same date number, and by 6 + (number of days difference between the particular dates) in more complex cases. Following the detailed step-by-step approach, however, keeps the logic transparent and easy to verify.

Why Other Options Are Wrong:
Tuesday or Wednesday would result from a smaller shift than the one created by two 31-day months. Friday or Saturday would correspond to a larger forward shift than the two blocks of 31 days actually produce. Only Thursday matches the precise day counting.

Common Pitfalls:

• Confusing the weekday of the 2nd day with that of the 1st day and not adjusting correctly.
• Incorrectly assuming that every 31-day month shifts the next month's start by 1 day instead of 3.
• Miscounting the number of days between dates and skipping the 28-days-equals-4-weeks idea.

Final Answer:
The last day of the next 31-day month will be a Thursday.