A map has a scale off 1:20000
Find the actual length, in kilometres, of a road which is 4cm long on the map

Question

anonymous · Answer

4 * 20000
= 80000 km

anonymous · Answer

Use dimensional analysis, and cancel out the unit cm.
$$(4cm)(2000km/1cm)=8000km$$

anonymous · Answer

1cm:20000cm

4cm=80000cm

80000cm=0.8km

anonymous · Answer

Yeah, I kinda got the same answer as Zed, just reassuring, thanks to all

anonymous · Answer

That can't be the answer because we are talking about a scale, not some conversion.

anonymous · Answer

What? Bro the question's asking for the orig length

anonymous · Answer

I was kinda referring to the 0.8km.
What I meant was that the answer should be 8000 km, not 0.8 km.

phi · Answer

FYI from http://egsc.usgs.gov/isb/pubs/factsheets/fs01502.html A map scale usually is given as a fraction or a ratio—1/10,000 or 1:10,000. These "representative fraction" scales mean that 1 unit of measurement on the map—1 inch or 1 centimeter—represents 10,000 of the same units on the ground. If the scale were 1:63,360, for instance, then 1 inch on the map would represent 63,360 inches, or 1 mile,

anonymous · Answer

Oh, then it's my bad. Sorry.
Zed's answer would then be correct.