On Wed, 20 Jan 2010 17:00:45 -0800, Darren New wrote:

> Jim Henderson wrote:
>> That makes more sense - but fairly easy to answer algebraically.
> 
> That's why I think the original poster meant to ask the later questions,
> which are somewhat trickier.

Likely, yes.

>>>> And I'm not sure that discarding the length of the track allows the
>>>> question to be answered even then.
>>> No, that would eliminate the ability to answer.
>> 
>> How so?  If you know the distances and speeds,
> 
> Oh, you're discarding the length of the track, but you still know the
> distances?

Wait, what?  No, I was saying that the length of the track is a critical 
missing piece of information in the original question (the question 
specifically states the length doesn't matter - but I believe it does).

> I don't understand, but ... nevermind. :-)

Are we having one of our "we're both saying the same thing" moments 
again? ;-)

>>> You want to average 60MPH over two minutes. You go 30MPH for the first
>>> mile. How fast do you have to go to average 60MPH for two minues?
>>>
>>> Second alternate question: you want to average 60 MPH. You drive 10
>>> miles at 30MPH. How many miles do you need to drive at 90MPH to
>>> average 60MPH?
>> 
>> I agree, that question formulation would be easier to answer.
> 
> Well, except for the first one. And the second one is unobvious, easy to
> fall into a trap.

True.

Jim

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