Math Is Fun Forum

1a2b3c2212

Member

Registered: 2009-04-04

Posts: 419

Speed Problem

A man plans on arriving by train at the station at 3:00pm and then plans to have his wife drive him home. Instead, he catches an earlier train and arrives at the station at 2.00pm. He decides to walk toward home and is picked up by his punctual wife en route. They arrive home twenty minutes earlier than planned. How long did he walk?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Speed Problem

Hi 1a2b3c2212;

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,623

Re: Speed Problem

hi bobbym,

How are you?  Haven't 'spoken to you' for a while.

So how did you get this result?

I keep going round in circles for lack of another bit of data.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Speed Problem

Hi bob bundy;

How are you?  Haven't 'spoken to you' for a while.

According to my calculations by some coincidence I have not spoken to you in exactly the same amount of time.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,623

Re: Speed Problem

hi bobbym and 1a2b3c2212

My calculations suggest it is more than a coincidence.  Maybe there's a whole new branch of math here.

Your hint was just what I needed.  I thought that not knowing the distances and speeds made this too vague but what I was forgetting is that the wife has to set out from home (at the same speed we assume) in order to arrive at 3pm.  That's a new bit of information I was forgetting.  So I have modified my diagram which I have named in your honour.

Each square across represents 10 mins.  The scale for distance is not needed as it could be anything.

Bob

Last edited by Bob (2011-04-01 21:14:59)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Speed Problem

Hi Bob;

My calculations suggest it is more than a coincidence.  Maybe there's a whole new branch of math here.

Let's not jump to conclusions here. The scientific method demands caution and patience and a few NSF grants.

Nice diagram!

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,623

Re: Speed Problem

hi bobbym,

Grants?  I was hoping for a 'professorship' and department in a major University.

btw.  My longer term project has not yet yielded a result.  I've ended up on a rolling surface in 6 dimensional space, trying to 'roll' to the lowest point.  I got to within 0.6 units of the point I wanted just using Excel, but I think the real bottom point is not close so I'm having a re-think.

Got anything that will solve 6 simultaneous equations in 6 unknowns?

Bob

Last edited by Bob (2011-04-01 22:29:00)

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Speed Problem

Okay, I will send the grant money back. I think collaboration on a book or two might be more rewarding.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.