Given sequence is geometric sequence and common ratio between consecutive term is
In Arithmetic sequence , common difference between consecutive terms should be equal.
In Geometric sequence, common ratio between consecutive terms should be equal.
Given sequence, 16, 8, 4, ...
Since, common difference = 8 - 16 ≠ 4 - 8 , this is not arithmetic sequence.
Common ratio = T2/T1 = T3/T2 = 8/16 = 4/8 = 1/2 Because common ratio is are equal. Thus, given sequence is geometric sequence.
Hence the sequence is a geometric sequence and the common ratio = 1/2