Answer:
The answer to your question is: 21 seconds
Explanation:
Data
speed = v = 69 km/h
distance = d = 400 m
time = t = ?
Formula
v = d / t
t = d / v
Process
Convert 400 m to km
1 km ----------------- 1000 m
x ------------------- 400 m
x = (400 x 1) / 1000
x = 0.4 km
Substitution
t = 0.4 / 69
t = 0.006 h
Covert time to minutes and seconds
60 min -------------------- 1 h
x ------------------- 0.006 h
x = (0.006 x 60) / 1
x = 0.36 min
Convert time to seconds
1 min ------------------ 60 s
0.36 min -------------- x
x = (0.36 x 60) / 1
x = 21.6 seconds ≈ 21 seconds
