A blacksmith has five iron articles A, B, C, D and E, each having a different weight.
(i)  A weights twice as much as B.
(ii)  B weights four and a half times as much as C.
(iii)  C weights half as much as D.
(iv)  D weights half as much as E.
(v)  E weights less than A but more than C. Which of the above given statements is not necessary to determine the correct order of articles according to their weights ?

Answer: E. 5

Let C's weight be x.
Then, D's weight is 2x. E's weight is 4x. B's weight is 4.5x and A's weight is 9x.
So, the order of weights can be A > B > E > D > C.

Clearly, statement (5) is not required to determine the order of weights.