Speed ratio of dog and rabbit:

( 1/4)/( 1/5):( 1/7)/( 1/6)=35:24

That is, for every 35 meters a dog runs, a rabbit can run 24 meters.

Dogs run 35-24 meters more than rabbits = 1 1 meter.

The dog caught up with the rabbit and ran 550 meters more than the rabbit.

You need to run 550/ 1 1=50 times 35 meters.

So the dog ran after the rabbit:

50× 35 = 1750m

2.

From Xiao Li chasing Xiao Wang to their second meeting,

Xiao Li walked twice the distance from M to B.

Xiao Wang walked twice the distance from m to a.

The speed ratio of Xiao Li and Xiao Wang is 15: 10 = 3: 2.

So the distance ratio between m and b, m and a is 3: 2.

So the distance from A to M is 2/(2+3)×60=24 km.

It took Xiao Wang 24/ 10=2.4 hours to get to M.

It took Xiao Li 24/ 15= 1.6 hours to get to M.

So Xiao Li left 2.4- 1.6=0.8 hours =48 minutes later than Xiao Wang.

So when Xiao Li set off, it was 8: 48 in the morning.