The sub-duplicate ratio of 16:64 is Answers.
A) 4 : 3  B) 1 : 2  C) 1 : 3  D) 1 : 4  E) 2 : 4

Rationale: "root ( 16 ) : root ( 64 ) = 4 : 8 = 2 : 4 answer : e"
Answer: E