Small and Greater date require according to the weeknum

Hello Everyone,

I have a data in which column A contains Year, column B contains Week_number and column C contains Date. In column D I need a formula to track the 1st date _last date for the particular week number. for ex:- If I Select Week number 40, column D contains the date 28-Sep-2014 to 4-Oct-2014.

Thanks in Advance
Nisha