Apaperback book has a length of 6 in, a width of 9 in, and a height of 3 in. a book key chain is a 1/3 scale model of the book. what is the surface area ratio of the key chain to the book? *

answers

3

9

1/3

1/9

Since the surface area of a prism is
A = 2lw + 2lh + 2wh
then the surface of the 1/3 scale key chain will be:

A = 2( l / 3 )( w / 3 ) + 2 ( l / 3 )( h / 3 ) + 2( w / 3 )( h / 3)
A = (2/9) ( lw ) + ( 2 / 9 ) ( lh ) + ( 2/9 ) ( wh)
A = ( 1 / 9 ) ( lw + 2lh + 2wh)

so the ratio of the key chain to the book is 1/9