How do you reduce 1.2km : 400 m?

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Answer 1 · 2017-02-14T10:26:28

#3:1#

Firstly change the #km# to metres.

#1.km:400m::1200m:400m#

the units now cancel and can be omitted.

#1200:400#

now cancel the numbers by their common factors

#1200:400::12:4#

#12:4::3:1#

Answer 2 · 2017-02-16T22:21:47

#1.2km:400m -> 3:1#

This is a ratio which if you so chose is permissible to write in fraction FORMAT. Do not confuse this with a fraction

So write #" "1.2km:400m" "# as #" "(1.2Km)/(400m)#

Known that 1 km is the same as 1000 m. So we can convert the Km into m so that both values are using the same units of measurement.

#"(1.2Km)/(400m)##-=##(1.2xx1000)/400# in metres

The #-=# means equivalent to

#=(1.2xx10xxcancel(100))/(4xxcancel(100)) = 12/4 -=(12-:4)/(4-:4) = 3/1#

Remember that this is a ratio

So 1.2 km : 400 m is the same as 3 : 1