Answer: Perimeter and Area of the final poster will be 168 cm and 1728 cm² respectively.
Explanation:
Since we have given that
Each student is to design a school poster.
Dimensions of rectangle are :

It is then dilated by a scale factor of 3.
So, Perimeter of the final poster becomes

Similarly, Area of the final poster becomes

Hence, Perimeter and Area of the final poster will be 168 cm and 1728 cm² respectively.