Answer:
Ratio of the perimeters =3:1
Step-by-step explanation: 
 We have given that : Ratio of the sides of two squares is 3:1
To find : Ratio of their perimeters 
Solution : Let the length of the sides are 3:1 = 3x : x
                   Formula of perimeter of square = 4(side)
 Using the formula , 
Perimeter of 1 square = 4×3x= 12x
Perimeter of 2 square = 4×x= 4x
Ratio of the perimeter of 1 square and 2 square = 12x : 4x
                                                                                  = 3 : 1