Draw 5 boxes. split them into 3rds and color 2 thirds of yeach of them
1cm : 3m
to get from 12m to 3m you have to divide by 4, so if:
3 x 4 = 12
then you do the same to the 1cm and you get:
1 x 4 = 4
Therefore:
1cm : 3m
4cm : 12cm
the model is 4cm
the answer is the above in bold
hope it helped :)
and sry if my explanation wasn't detailed enough or if i misunderstood the question
Answer:
The answer is in the included image