A compound pipeline consists of two pieces of identical pipes. The equivalent length of the same diameter and the same friction factor for this compound pipeline is L1 when the pipes are connected in series and is L2 when the pipes are connected in parallel. Determine the ratio of equivalent lengths, that is, L1 to L2.
1
32 ∶ 1
2
4 ∶ 1
3
8 ∶ 1
4
64 ∶ 1