A car travels 80 miles in 11 hours. What is its average speed?

The average speed is 7.2727273 mph.

v = \frac{d}{t} = \frac{80}{11} = 7.2727273\ \text{mph}

How to work it out

1
Write down what you know: distance d = 80 miles, time t = 11 hours. You are asked for the speed v.
2
Use the formula speed = distance ÷ time:
$v = \frac{d}{t} = \frac{80}{11} = \frac{80}{11} = 7.2727273$
3
Answer with the unit: 7.2727273 mph.
4
The same formula rearranged: distance = speed × time (7.2727273 × 11 = 80 miles) and time = distance ÷ speed (80 ÷ 7.2727273 = 11 hours).

LaTeX source of the formulas on this page

\[ v = \frac{d}{t} = \frac{80}{11} = 7.2727273\ \text{mph} \]
\[ v = \frac{d}{t} = \frac{80}{11} = \frac{80}{11} = 7.2727273 \]

What is the speed if a car travels 80 miles in 11 hours?

The average speed is 7.2727273 mph.

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

21.818182 miles.