Calendar reasoning – Mohini went to the movies exactly nine days ago. She goes to the movies only on Thursdays. Based on this information, what day of the week is it today?

Introduction / Context:
Questions about days of the week often test your ability to translate a verbal description into a precise offset on a 7-day cycle. Here, the key is that Mohini goes to the movies only on Thursdays and she last went “nine days ago.” We must map “nine days ago” onto the weekly cycle to infer today's day.

Given Data / Assumptions:

• Mohini goes to the movies only on Thursday.
• She went to the movies exactly 9 days ago.
• Weekdays repeat every 7 days (mod 7 arithmetic).

Concept / Approach:
The weekday d days ago is obtained by moving d steps backward on a 7-day cycle. Equivalently, moving forward by d days changes the weekday by d mod 7. Since movie day is Thursday, “9 days ago” being a movie day means 9 days ago was Thursday. Add 9 days to get today: 9 mod 7 = 2, so today is two days after Thursday.

Step-by-Step Solution:

Verification / Alternative check:
Count explicitly backward from today (unknown) by 9 to land on Thursday. If today were Saturday, going back 9 days lands on Thursday (Saturday → Friday (1), Thursday (2), Wednesday (3), Tuesday (4), Monday (5), Sunday (6), Saturday (7), Friday (8), Thursday (9)). This confirms the result.

Why Other Options Are Wrong:

• Thursday: Would imply zero or multiples of seven days difference, not nine.
• Sunday: Two days after Friday, not after Thursday; mismatch.
• Tuesday: Five days after Thursday; not equal to 9 mod 7 = 2.
• None of these: There is a matching option (Saturday), so this is incorrect.

Common Pitfalls:
Forgetting to reduce by mod 7; counting 9 days as “1 week and 1 day” but then adding in the wrong direction; assuming “only Thursday” implies some other constraint. Always reduce offsets modulo 7 and move in the correct direction.

Final Answer:
Saturday