Surface Area help!

Question

The inner dimensions of an in-ground swimming pool are: width = 13.0ft, length = 18.0 ft, and depth = 9.0ft. The pool walls and the bottom are uniformly 1.0 ft thick and made of concrete. What is the total concrete surface area of the pool in units of ft2?

Answer 1

 

   Imagine the Olympic swimmer diving into the pool

   and swimming the entire length.

 

   From the point of view from the Olympic swimmer,

   the surface area is:

 

       15 x 1 + 8 x 1 + 8 x 1 + 15 + 8 + 8 = 31.

   The other side is the same, so double that is 62.

 

  THere are two side walls:

       THe surface area is 18 x 1 + 18 x 1 + 9 x 1 + 9 x 1 + 18 x 9 + 18 x 9

                                    = 18 + 18 + 9 + 9 + 162 + 162 = 378.

       The other wall is exactly the same, so double that is  756.

 

 Finally there is the bottom of the pool.

        2 x 18 x 1 + 2 x 1 x 13 + 2 x 13 x 18 =

         36 + 26 +  468 = 530

 

Total 1348

 

  

   

       

Answer 2

bottom: 11 x 16      (minus 2 feet for walls)

two sides: 16 x 8     (minus 1 foot for bottom)                 "

two sides: 11 x 8                  "

 

Can you calculate surface area?