How to maintain state for Radio Buttons in Listbox

Question

Hi,

I am displaying question paper with radiobuttons as options. i done the paging for listbox using datapager control. now i select radiobuttons for all questions in the first page and click on next button againg i selected radio buttons in that page too. after that i went to previous page now all radio buttons what i selected is deselected . now i want to keep all radiobuttons select mode what i selected in every page . how can i achieve this . please help me.
Thanks&Regards
P.Nagaraju