Hi Ranjith,
Not sure if you are trying to get estimates, or trying to derive one column out of other column values in reports. If you are dealing with existing stats, then some useful formulae are:
Ctr = Clicks / Impressions
Total Cost = Sum (clicks * cpc for those clicks) // since you may have changed your bid in between.
AverageCpc = Total Cost / sum(Clicks)
Cheers,
Anash P. Oommen,
AdWords API Advisor.