Use at interface: 0.25× 2 = 0.5m.

Length of connecting rope: 7.5-0.5=7m.

Method 2: Remove the joint of a rope, and the remaining length is 3.75-0.25 = 3.5m.

The total length of two ropes after connection: 3.5*2=7m.

Extended data:

For this kind of problem, it is mainly to understand that the length of the connected rope is shortened by two 0.25m m.

Similar problem: use two ropes 1.35 meters long to tie the carton, and the joint should be 0.3 meters. How long is the connected rope?

Formula: 2 *1.35-0.3 = 2.4m.

Answer: After connection, the rope is 2.4 meters.