It's just impossible in theory; you don't need to know anything else than:
-syndra's E pushes her spheres to 1100 range at 2500 speed, no matter where she puts her spheres.
the range of her E is 700, if she puts her Q on max range and then presses E, the spheres will move by 400 at a speed of 2500, in other world thanks to the formula t= d/v , her E will reach you in 400/2500 seconds, (0.16 seconds)
if you're character has 400 ms, he can move at a speed of 400 units/seconds, which is effectively 64 units/0.16 seconds
the only way you can dodge her E is because:
-the player is dumb af, and didn't put his Q at max range of his E
-the player is dumb af, and didn't put his Q right behind you (and then missed his E)