Sanjiv,
Yes... the CAPM exam is a knowledge based exam that is 100% based on the PMBOK Guide. So if you know and understand the formulas in the PMBOK Guide (and are able to apply them) then you will do just fine. The questions with formulas will be rather straightforward calculations.
However... I cannot say how many formula questions you will have on your exam, because the exam is random. You may see 1, you may see 5, you may see 7. It's just a matter of "chance", how your particular exam is composed.