The sequences with a common ratio of 1/4 are:
512, 128, 32, 8, ...
256, 64, 16, 4, ...
320, 80, 20, 5, ...
768, 192, 48, 12, ...
560, 140, 36, 9, ...
The others have a common ratio of 4.
The common ratio is found by dividing the second term by the first term. For instance, in the first sequence, we would have 28/7 = 4. In the second sequence, we have 128/512 = 1/4.
