A car travels 420 miles in 3 hours. What is its average speed?
The average speed is 140 mph.
How to work it out
- 1
Write down what you know: distance d = 420 miles, time t = 3 hours. You are asked for the speed v.
- 2
Use the formula speed = distance ÷ time:
- 3
Answer with the unit: 140 mph.
- 4
The same formula rearranged: distance = speed × time (140 × 3 = 420 miles) and time = distance ÷ speed (420 ÷ 140 = 3 hours).
LaTeX source of the formulas on this page
\[ v = \frac{d}{t} = \frac{420}{3} = 140\ \text{mph} \]
\[ v = \frac{d}{t} = \frac{420}{3} = 140 \]How far at 140 mph
| Time | Distance |
|---|---|
| 0.5 hours | 70 miles |
| 1 hour | 140 miles |
| 2 hours | 280 miles |
| 3 hours | 420 miles |
| 4 hours | 560 miles |
| 5 hours | 700 miles |
Questions
What is the speed if a car travels 420 miles in 3 hours?
The average speed is 140 mph.
How far does it go in 3 hours at that speed?
420 miles.