Divit has his birthday on Friday, 30th June. In the same calendar year Samar was born on 15th November. On which day of the week does the birthday of Samar fall in that year?

Introduction / Context:
This is another calendar arithmetic question where you must move from one known date and day of the week to another date in the same year. The key is to count the number of days between the two dates correctly and then convert that into a weekday shift. This kind of reasoning is frequently tested in aptitude and banking examinations.

Given Data / Assumptions:

• Divit's birthday is on Friday, 30th June.
• Samar's birthday is on 15th November of the same year.
• We use the standard Gregorian calendar.
• Month lengths needed: July has 31 days, August has 31 days, September has 30 days, October has 31 days, and November has 30 days in total.

Concept / Approach:
We count how many days elapse from 30th June to 15th November and then reduce this number modulo 7. The remainder tells us how many days to move forward from Friday to reach the weekday for 15th November. It is important to handle the boundary dates carefully and ensure the day count is accurate.

Step-by-Step Solution:
Step 1: Consider the period starting from the day after 30th June. From 1st July to 31st July there are 31 days.Step 2: August has 31 days.Step 3: September has 30 days.Step 4: October has 31 days.Step 5: In November, we need to go from 1st November to 15th November inclusive, which is 15 days.Step 6: Add these intervals to get the total number of days between 30th June and 15th November: 31 + 31 + 30 + 31 + 15.Step 7: Calculate 31 + 31 = 62, 62 + 30 = 92, 92 + 31 = 123, 123 + 15 = 138 days.Step 8: Find 138 modulo 7. Since 7 * 19 = 133, the remainder is 138 - 133 = 5.Step 9: A difference of 138 days corresponds to moving forward 5 days in the week cycle.Step 10: Starting from Friday, move 5 days forward: Saturday (1), Sunday (2), Monday (3), Tuesday (4), Wednesday (5).

Verification / Alternative check:
We can confirm by grouping days into multiples of seven. After 7, 14, 21 and so on days from Friday, the day of the week cycles back to Friday each time. After 133 days (which is 19 full weeks), it will again be Friday. The remaining 5 days then move you to Wednesday. This double checks that the modulo operation and the step by step weekday counting are both consistent.

Why Other Options Are Wrong:
Tuesday would result from a forward shift of 4 days, which does not match the remainder of 5.Friday would correspond to a shift of 0 days modulo 7, which is not the case here.Saturday would correspond to a shift of just 1 day, and Monday would correspond to a shift of 3 days, both of which contradict the calculated shift of 5.

Common Pitfalls:
Students sometimes miscount the number of days in one of the months or incorrectly handle the inclusive or exclusive nature of the endpoints. A good method is to separately write down the days in each month and then sum them carefully, as shown. Forgetting to reduce the total days modulo 7 and instead stepping one by one over all days is also inefficient and prone to error. Using the modulo approach is much cleaner and more reliable.

Final Answer:
In that year, Samar's birthday on 15th November falls on Wednesday.