Each week Manhattan GMAT posts a GMAT question on our blog and follows up with the answer the next day. Are you up for the challenge?
A geometric sequence is one in which the ratio of any term after the first to the preceding term is a constant. If the letters a, b, c, d represent a geometric sequence in normal alphabetical order, which of the following must also represent a geometric sequence for all values of k?
I. dk, ck, bk, ak
II. a + k, b + 2k, c + 3k, d + 4k
III. ak4, bk3, ck2, dk
(A) I only
(B) I and II only
(C) II and III only
(D) I and III only
(E) I, II, and III