Kavya birthday in a particular year falls on Tuesday, 4 July. In that same year, Anika was born on 15 August. On which day of the week will Anika birthday fall?

Introduction / Context:
This day of week problem relates two birthdays in the same year. We know the day for 4 July and must find the weekday for 15 August of that year. It tests your ability to count days across part of July and the first half of August and then correctly convert that count into a weekday shift using multiples of seven days.

Given Data / Assumptions:
- Kavya birthday is on Tuesday, 4 July. - Anika birthday is on 15 August in the same year. - Take a normal non leap year for month lengths. - Month lengths used: July 31 days, August 31 days.

Concept / Approach:
The weekday for a later date can be obtained by counting the number of days between the known date and the target date, then taking this difference modulo 7. Because every seven days the weekday cycle repeats, only the remainder affects the weekday. We move from 4 July to 15 August, summing days within July and early August, and then shift Tuesday forward by the appropriate remainder number of days.

Step-by-Step Solution:
Step 1: Count days remaining in July after 4 July. July has 31 days, so days from 5 July to 31 July inclusive are 31 - 4 = 27 days. Step 2: Count days from 1 August to 15 August inclusive. That gives 15 days. Step 3: Total days from 5 July to 15 August inclusive of 15 August are 27 + 15 = 42 days. Step 4: The difference between 4 July and 15 August is 42 days. Step 5: Compute 42 mod 7. Since 42 equals exactly 7 times 6, the remainder is 0. Step 6: A remainder of 0 means there is an exact number of complete weeks between the two dates. Step 7: Therefore, the weekday on 15 August is the same as on 4 July. Step 8: Since 4 July is Tuesday, 15 August is also Tuesday.

Verification / Alternative check:
Because 42 days is exactly 6 weeks, you can view this as six full cycles of the weekday pattern. When you add a full week, the weekday does not change. Repeating this six times confirms that the starting and ending weekdays must match without even having to step through intermediate days. This simple reasoning strongly confirms that Anika birthday falls on the same weekday as Kavya birthday.

Why Other Options Are Wrong:
- Wednesday, Thursday, Friday, or Saturday would require a non zero remainder when dividing the day difference by 7. For example, a remainder of 1 would give Wednesday, 2 would give Thursday, and so on. - Because the remainder is 0, none of these shifted weekdays fits the calculation.

Common Pitfalls:
Students sometimes miscount the number of days in July or count from 4 July instead of from the following day, leading to 41 or 43 days and hence a wrong remainder. Another common issue is forgetting that the target date is included in the count. Always check the day counts carefully, then convert the total to a remainder modulo 7 before adjusting the weekday.

Final Answer:
Anika birthday on 15 August in that year will fall on Tuesday.