Kavya's birthday in a certain year falls on Tuesday, 4th July. In the same year, Anika was born on 15th August. On which day of the week does Anika's birthday fall?

Introduction / Context:
This calendar question asks you to determine the day of the week for one date when the weekday of another date in the same year is given. Such questions are very common in aptitude tests because they test your understanding of how days progress through the months and how to count the number of days between two given dates without memorising every calendar.

Given Data / Assumptions:

• Kavya's birthday is on Tuesday, 4th July of a particular year.
• Anika's birthday is on 15th August of the same year.
• The year is treated as a normal Gregorian calendar year; the relative difference between dates after February does not depend on whether the year is leap or non-leap.
• We must find the day of the week on 15th August of that year.

Concept / Approach:
To relate two dates in the same year, we count the exact number of days between them and then convert this difference into a number of whole weeks and extra days. Every complete week (7 days) returns the same weekday, and the remainder tells us how many days ahead (or behind) the second date is from the first date. Because both dates are after February, the leap year effect does not change the difference between 4th July and 15th August.

Step-by-Step Solution:
Step 1: Start from 4th July and move to 31st July. Step 2: The number of days from 4th July to 31st July = 31 - 4 = 27 days. Step 3: Now count days from 1st August to 15th August = 15 days. Step 4: Total days between 4th July and 15th August = 27 + 15 = 42 days. Step 5: Divide 42 by 7 to find the number of weeks: 42 / 7 = 6 complete weeks with 0 extra days. Step 6: Six complete weeks later, the day of the week remains unchanged from Tuesday. Step 7: Therefore, 15th August falls on a Tuesday.

Verification / Alternative check:
Another way is to reason directly: whenever the difference between two dates within the same year is a multiple of 7 days (here 42 days), the weekday will repeat. Since we have already shown that the difference is 42 days, which is exactly 6 weeks, there is no need to handle any additional remainders. Hence, the day for 15th August is the same as that for 4th July, confirming that it is Tuesday.

Why Other Options Are Wrong:
Monday: This would correspond to a shift of one day backward, which would require the difference to be 41 or 48 days with a specific modulo 7 remainder, which is not the case here.
Wednesday: This would require a remainder of 1 when dividing by 7, but the difference of 42 days is divisible exactly by 7.
Thursday: This would require a shift of two days ahead, corresponding to a remainder of 2, which does not match 42 days.
Friday: This implies a remainder of 3 days beyond complete weeks, again not consistent with 42 being a multiple of 7.

Common Pitfalls:
Students sometimes miscount the number of days by including the starting date incorrectly or by forgetting that 4th July to 31st July is 27 days and not 28. Another frequent error is to worry about whether the year is leap or non-leap. For dates that both fall after February, the leap day (29th February) has already occurred or not occurred, but it affects both dates equally, so the difference between them stays the same. Mixing up inclusive and exclusive counting for dates is another common source of mistakes.

Final Answer:
Therefore, Anika's birthday on 15th August in the same year falls on Tuesday.