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.