A car travels 400 km in 7 hours. What is its average speed?

The average speed is 57.142857 km/h.

v = \frac{d}{t} = \frac{400}{7} = 57.142857\ \text{km/h}

How to work it out

1
Write down what you know: distance d = 400 km, time t = 7 hours. You are asked for the speed v.
2
Use the formula speed = distance ÷ time:
$v = \frac{d}{t} = \frac{400}{7} = \frac{400}{7} = 57.142857$
3
Answer with the unit: 57.142857 km/h.
4
The same formula rearranged: distance = speed × time (57.142857 × 7 = 400 km) and time = distance ÷ speed (400 ÷ 57.142857 = 7 hours).

LaTeX source of the formulas on this page

\[ v = \frac{d}{t} = \frac{400}{7} = 57.142857\ \text{km/h} \]
\[ v = \frac{d}{t} = \frac{400}{7} = \frac{400}{7} = 57.142857 \]

What is the speed if a car travels 400 km in 7 hours?

The average speed is 57.142857 km/h.

How far does it go in 3 hours at that speed?

171.42857 km.