# Speed, distance and time

Last updated: 22 Nov 2008

There is some special vocabulary that we use when we describe rates of travel.

'Rate of travel' is speed (or average speed)

'Amount travelled' is distance

This is just another way of describing rates so we can restate the rate formula's from the previous page as

\[
\begin{split}
\text{Average speed} &= \frac{\text{Distance}}{\text{Time}} \\
\text{Time} &= \frac{\text{Distance}}{\text{Average Speed}} \\
\text{Distance} &= \text{Average Speed} \times \text{Time}
\end{split}
\]

### Average speed example

If a car travels 300 miles in 6 hours then what is it's average speed?

Speed is just another way of saying the rate at which you travel so

\[
\begin{split}
\text{Average speed} &= \frac{\text{Distance}}{\text{Time}} \\
&= \frac{300 \text{ miles}}{6 \text{ hours}} \\
&= 50 \text{mph}
\end{split}
\]

If Michael is driving to his Aunt Pam's house at an average speed of 40 mph and returns the same route at an average speed of 60 mph. Approximately what was the avg. speed for the round trip?

This speed distance practice problem is very similar, try it and then look at the review and it should make it clear how to answer the question you have asked.

Best of luck.

PLS HELP ME WITH THIS PROBLEM I CAN'T READ ANY OF YOUR MATH TUTORIALS I ALWAYS GET THISA

verage speed = = 50 mph

HOW CAN I READ THAT?

PLS I NEED YOUR HELP.

THANKS,

LABINA

The average speed would be 2D/(D/40+D/60) = 48mph

You can also use the harmonic mean, which is n / [(1/x1) + (1/x2) + ... + (1/xn)]