A manufacturer wants to double the volume of his graham cracker box. They will either double the height or double the width. Which one will use less cardboard and how much less cardboard.
Original area 2 ( 6*2 + 6*9 + 2*9) = 168 in^2
double h (from 9 to 18) area 2 ( 6*2 + 6*18 + 2*18) = 313 in^2
double w ( from 2 to 4 ) area 2 ( 6*4 + 6*9 + 4*9) = 228 in^2
Doubling w will use (312 - 228) = 84 in2 less material
Original area 2 ( 6*2 + 6*9 + 2*9) = 168 in^2
double h (from 9 to 18) area 2 ( 6*2 + 6*18 + 2*18) = 312 in^2 Fixed typo
double w ( from 2 to 4 ) area 2 ( 6*4 + 6*9 + 4*9) = 228 in^2
Doubling w will use (312 - 228) = 84 in2 less material