The first 1500 m the bus moved at a speed of 25 m / s, then for 40 s it moved at a speed of 20 m / s, after stopping for 70 s

The first 1500 m the bus moved at a speed of 25 m / s, then for 40 s it moved at a speed of 20 m / s, after stopping for 70 s, the bus covered the last 900 m in 30 s. Find the average speed of the bus along the way.

In this case, the average speed will be calculated as the ratio of the entire path to the entire time spent:
Vav = Sп / Tп
Given:
t1 = s1 / v1 = 1500/25 = 60 s.
t2 = s2 / v2 = 40 s.
s2 = v2 * t2 = 20 * 40 = 800 m
t3 = 70 s.
s3 = 0 m
t4 = 30 s.
s4 = 900 m
Sп = s1 + s2 + s3 + s4 = 1500 + 800 + 0 + 900 = 3200 m
Tp = t1 + t2 + t3 + t4 = 60 + 40 + 70 + 30 = 200 s.
Answer: Vav = 3200/200 = 16 m / s – average bus speed