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December 12th, 2016, 11:38 AM   #1
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lorry journey

a

Last edited by markosheehan; December 12th, 2016 at 11:41 AM.
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December 13th, 2016, 09:02 PM   #2
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Quite a journey indeed.
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December 16th, 2016, 11:09 AM   #3
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I made the post and then I figured it out, but I didn't know how to delete it, so instead of people working it out I thought I would just edit it and delete the text.

Last edited by skipjack; December 16th, 2016 at 01:13 PM.
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December 16th, 2016, 12:42 PM   #4
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Quote:
Originally Posted by markosheehan View Post
I made the post and then I figured it out, but I didn't know how to delete it, so instead of people working it out I thought I would just edit it and delete the text.
Haha fair enough . After a certain time passes, you can no longer delete or edit your posts, in case you were wondering. But since you were able to edit, I guess you couldn't find the delete button.

Last edited by skipjack; December 16th, 2016 at 01:14 PM.
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December 16th, 2016, 02:05 PM   #5
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Say the lorry travels for times $t_1$, $t_2$ and $t_3$ at average speeds of v/2, v and v/2 respectively.

As $\dfrac{5v}{6} = \dfrac{t_1v/2 + t_2v + t_3v/2}{t_1 + t_2 + t_3}$, $\dfrac56(t_1 + t_2 + t_3) = t_1/2 + t_2 + t_3/2 = \dfrac12(t_1 + t_2 + t_3) + \dfrac12t_2$,

and so $t_2 = 2(5/6 - 1/2)(t_1 + t_2 + t_3) = \dfrac23(t_1 + t_2 + t_3)$.
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