7th Grade Challenging Math

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7-18)   Answer

           largest = 3120 square inch, smallest = 1380 square inch

Solution:
To get the largest surface area, you need to glue the smallest surfaces together, in this case 5 x 2 inch surfaces. Therefore, the largest surface area is:

(150 x 2 + 2 x 5 + 150 x 5) x 2 = 3120 square inch

To get the smallest surface area, you need to glue the largest surfaces together, in this case 50 x 5 inch surfaces. Therefore, the smallest surface area is:

(50 x 8 + 8 x 5 + 50 x 5) x 2 = 1380 square inch