Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**Denominator****Member**- Registered: 2009-11-23
- Posts: 155

Yes, I understand this now

Thank you bob and bobby and anonim!

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi Denominator;

Your welcome!

**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.**

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,541

You are very welcome.

Bob

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 Bundy

Offline

**Monox D. I-Fly****Member**- From: Indonesia
- Registered: 2015-12-02
- Posts: 1,681

bob bundy wrote:

hi Denominator

Let the distance from Southampton to London be D, and the distance to the overtaking point be d.

Let the time in minutes from 9.17 to the overtaking point be t

The goods train takes 165 minutes

The express train takes 100 minutesSo the gradient (velocity in miles / min) for the goods train is

and for the express train

You can eliminate both D and d by dividing these equations:

and then solve for t.

Bob

How did you get that 39? Sorry, couldn't comprehend.

Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend who has passed away. May his adventurous soul rest in peace at heaven.

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,541

hi Monox D. I-Fly

The express train starts off later. See post #18.

Bob

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 Bundy

Offline

**Monox D. I-Fly****Member**- From: Indonesia
- Registered: 2015-12-02
- Posts: 1,681

Oh, I see. The difference between 09.56 and 09.17, right? Took me some minutes to figure it out.

Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend who has passed away. May his adventurous soul rest in peace at heaven.

Offline