if i qualify in isi(indian statistical institute) exam(ON 8TH MAY) but not join it will the qualification certificate BE IMPORTANT IN FUTURE like for some scholarship or something?????????please help soon

Absolutely no. It may only come in handy to show off in front of less intelligent people(especially friends, relations etc) that u got selected!!!!. otherwise it has no value. u know even the air of iit jee is useless if u don't join iit.