Phase Planning using Monte carlo

Dear all,

I have a following doubt can any give me suggestion how to do that,

I have 1 master project with me .it Consists of 3 Phases .I want to calculate the project duration,ie the best duration .

I like to know how Monte carlo Analysis fit in it.If i give a range of values as input ,ie max & min time for each phase it might give range of output.but my doubt is how good is it(duration)? These 3 phases are dependent each other.

Regards

Sankar Vijayan