Question

The surface area of a rectangular prism is 150 cm². If all the sides are tripled, what will the new surface area be?

Answer 1

1350

If the sides of the prism are of length a, b and c respectively, the corresponding surface area is \[SA_{old}=2[(a*b)+(b*c)+(a*c)]\]and if the sides are tripled it becomes\[SA_{new}=2(3a*3b)+2(3b*3c)+2(3a*3c)=18[(a*b)+(b*c)+(a*c)]\]thus the new surface area is 9 times that of the original