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## Homework Statement

The scale on a map is 1:25000. The lenght of a wall on the map is 3.2 mm. Find the actual length in metres.

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- Thread starter tehmatriks
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The scale on a map is 1:25000. The lenght of a wall on the map is 3.2 mm. Find the actual length in metres.

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Mark44

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EDIT: Fixed momentary lapse of brain.

Each 1 mm distance on the map represents 25,000 mm (= 25 meters) on the ground. If the length of some feature on the map happened to be 10 mm, you would set up a proportion like this, where x represents the actual length of the feature, in mm.

[tex]\frac{1}{25000}=\frac{10}{x}[/tex]

After solving for x in this equation, convert to meters.

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Each 1 mm distance on the map represents 25,000 mm (= 2.5 meters) on the ground. If the length of some feature on the map happened to be 10 mm, you would set up a proportion like this, where x represents the actual length of the feature, in mm.

[tex]\frac{1}{25000}=\frac{10}{x}[/tex]

After solving for x in this equation, convert to meters.

25,000 x 3.2 = 80,000 x 10

- #4

Mentallic

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Either a typo or a brain fart, 25m :tongue:25,000 mm (= 2.5 meters)

It shouldn't be cm.25,000 x 3.2 = 80,000 x 10^{-3}= 80 cm

25,000 x 3.2 mm = 80,000 mm = 80,000 x 10

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yea, that was a typo

thanks fellas, i've just gotten to this chapter and the examples always leave out the good stuff, so many thanks.

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Mark44

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Unfortunately, the latter. It looked odd to me, but I still didn't catch it.Either a typo or a brain fart, 25m :tongue:

It shouldn't be cm.

25,000 x 3.2 mm = 80,000 mm = 80,000 x 10^{-3}m = 80 m

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