(2) How many kilometers per hour did you walk?

Solution: As you can see from the picture, the distance to walk is 5 kilometers and it takes 2/3 hours.

According to: speed = distance ÷ time, the average speed can be calculated as

5 ÷ 2/3 = 7.5 (km/h)

(3) How many kilometers per hour is the average round-trip speed in Xiaohu Li? (except the time of borrowing books)

Solution:

As can be seen from the figure,

Round trip distance: 5× 2 = 10 (km).

Round trip time: 2/3+ 1 = 5/3 (hours)

The round-trip speed is:

5×2÷(5/3)

= 10÷5/3

= 6 (km/h)