classification question

Hi.

Working with a data set like:
"age", "demographic data (n fields)", "interests(n fields)" has 
performed X actions for event Y.

I want to ask how likely is it for another person with his/her age, 
demographic data and interests to perform actions for that event.

My query set might be partial (eg just age or interests).

Can R help me with this? If yes, could you point me in the right direction?

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Best,
M.