help in sequence?

Question

this is a Qs wich i can't solve can you help me??????????
Jo is practising pool on an American 9-ball pool table, where the balls are numbered from 1 to 9. Jo picks a geometric sequence and, if there are balls on the table whose numbers are in that sequence, then Jo pots all of them. Jo keeps picking geometric sequences (and potting the corresponding balls) until all nine balls have been potted.

If Jo is very good, and never misses a shot, what is the least number of geometric sequences that Jo needs to pick in order to clear the table?

Answer 1

1,2,4,8 with r = 2
3,9 with r = 3
5,7 with r = 7/5
6
that's 4 sequences. 3,6,9 would be arithmetic, not geometric.

Answer 2

Three