Quote:
Originally Posted by
bluecobra
I read your answer and it is incorrect in relation to the original question asked as there is no time element put into place for the 2 mile or 60MPH avg to take place in.
60mph is a unit of speed (velocity), not time.
For example, there is no limitation to somebody speeding up to 120mph to make up "time" before the 2 mile marker comes up.
Bud is correct. It is a matter of definition. The average of 30 and 90 is 60 as numbers but not as speeds. The average speed is defined as the total distance divided by the total time. It is not a simple number but a rate which involves time. To calculate average speed, you need a weighted average. For example, if I go at 30 mph for 1 hour and then at 60 mph for 2 hours, the average speed is
((1)(30)+(2)(60))/(1+2)=50.
Note that this is just total distance divided by total time.