If you scale a certain figure with a scale factor of [tex] k [/tex], the sides will vary linearly, while areas will scale quadratically.
So, for example, if [tex] k=5 [/tex], the perimeter will be 5 times as much, while the area will be 25 times as much.
So, in your case, if the area scaled by 121/64, the perimeter scaled by
[tex] \sqrt{\dfrac{121}{64}}=\dfrac{11}{8} [/tex]
