I got 67.87 percent marks in t.y.b.sc but in f.y.b.sc and s.y.b.sc i only have 35 percent each. am i eligible for iit jam or iit m.sc admission?

i got 67.87 percent marks in t.y.b.sc(final year) but in f.y.b.sc and s.y.b.sc i only have 35 percent each. am i eligible for iit jam or iit m.sc admission? beacuse iit has criteria that one should have 55percentage aggregate marks in graduation.what is meant by aggregate marks?