So I ran across this problem in a test prep book (not homework):

Because that's not average speed. Average speed is total distance divided by total time. Never get your average speed by adding up speeds and dividing them by n.

>>8525382
Because speed is distance over time.
It becomes weighted if you try to average them.

If you want to average them correctly use the distance and time.

Also if I had a wood burning stove in my house I would want CO monitors.

>>8525442
>>8525464

Oh okay, that makes sense. Thanks!

>>8525382
>A man can drive 120 miles in either of two ways. Either he can travel at 40 mph the whole way, or he can do the first half at 50 mph and the second half at 30 mph.
awwwwww this is super cute baby's first algebra word problem. :) you have fun with that ;)

>>8525541

Well as I said, this is for a test (the GRE) so desu I am indeed enjoying the fact that the math for it isn't difficult.

>>8525382
If he spent half the _time_ going at 50, and the second half going at 30, it would take the same amount of time. But note that he'd cover 5/3 as much distance while going 50mph as he would at 30.

Is that the source of your intuitive confusion?

>>8525541
To be honest most normal people would probably get this wrong or at least second guess themselves. It's pretty unintuitive.

>>8525382
I think if it was for half the time and not half the distance it would work the way you thought

>>8525541

Can you take your smug attitude out of here, you fag?

You're the cancer that is ruining this board.

>>8525579
>>8525767
lets find out. call total time t:
x miles/50mph=t/2
y miles/30mph=t/2
x+y=120
x/50=y/30
x=5y/3
8y/3=120
y=45
t=2y/30=3 so yeah that's right.