I'm guessing you assumed he fired the arrow at an angle? If you assume he fires it vertically upwards (I guess because they normally make it clear if the object was fired/thrown or whatever at an angle) then you get the correct answer. Using v^2=u^2+2as with v=0, u=30 (you don't care about horizontal velocity since the arrow was fired vertically upwards), a=9.81 and s=? (remembering to add 1 to your value of s since it was fired from 1 metre above the ground).