sir i had secured 74.8% marks in cbse class 12 can i am eligible for jee adv 2017

@ shivangi 
all in the hand of JAB (jee admission board ) NOW , so, kindly drop a mail to them that u are nearly closer to the percentage , 
so, they may round it upto 75 , and u are elligible for mains 2017 , if they will not then u cannot give mains also . 
for advanced u need to stay within the top 75 percentile of the respective board , that will be declared with the board result itself . 
so, as of now u can hope best for mains . 
ALL THE BEST