If 15 December 2006 is a Friday, then what will the day of the week on 13 October 2009?

Given: 15 December 2006 is a Friday.
Logic: Count the number of days between 15 December 2006 and 13 October 2009:

15 December 2006 is a Friday, then what will the day of the week on 13 October 2009

Total no of days between 13 October to 15 December = 18 + 30 + 15

= 63 days 

Total no of odd days in 63 days = 63 $$\div$$ 7 = 9, Total odd days = 0

Thus, on 13 October will be Friday. 

Total odd days between 13 October 2006 to 13 October 2009 = 4 days (Because 2008 is a leap year.)

4 days after Friday is Tuesday.
Final Answer: (d) Tuesday ​​