A girl ran 41 miles with the wind at her back and then ran 39 miles in the same amount of time with the wind against her. if her pace without any wind is 8 miles/hr, how fast is the wind?

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- Nov 30th 2009, 05:25 AMsharkmanSpeed of Wind
*A girl ran 41 miles with the wind at her back and then ran 39 miles in the same amount of time with the wind against her. if her pace without any wind is 8 miles/hr, how fast is the wind?*

- Nov 30th 2009, 06:28 AMmasters
Hi sharkman,

If we believe that the wind will aid a runner the same way that a current would aid a boat, then

Let w = rate of wind

Let w + 8 = rate of girl with the wind (traveling 41 miles)

Let w - 8 = rate of girl against the wind (traveling 39 miles)

D = rt

Since t is constant, t = D/r

$\displaystyle \frac{41}{8+w}=\frac{39}{8-w}$ - Nov 30th 2009, 09:23 AMsharkmanThanks
- Dec 1st 2009, 03:11 AMHallsofIvy
But, of course, the wind does NOT "aid a runner the same way that a current would aid a boat" (or as wind aids an airplane). The wind blows against a runner setting up a slight amount of resistance. The boat floats

**on**the current so the current is added to its motion through the water- imagine a toy car running on table while the table is carried to one side.

In my opinion, this is a completely mistaken problem. - Dec 1st 2009, 06:02 AMsharkmanok
- Dec 1st 2009, 07:15 AMmasters