> if you do half your trip and 10mph and the other at 20mph your average isn't 15mph. You spent more time at 10mph!
If you're measuring "half your trip" in terms of distance covered, sure. If "half your trip" refers to half the total time, then your average is exactly 15 mph.
> And why do 3 buses come at once? Because the first one takes all the passengers, so stops more and gets slowed down. The other 2 catch up.
This is not related to the other phenomena you mention; as described here, the buses are actually being driven together as opposed to varying randomly.
And why do 3 buses come at once? Because the first one takes all the passengers, so stops more and gets slowed down. The other 2 catch up.
And also if you do half your trip and 10mph and the other at 20mph your average isn't 15mph. You spent more time at 10mph!