Question

The aluminum foil in a package containing 75 square feet of foil weighs 12 ounces. aluminum has a density of 2.70 g/ cm3. what is the approximate thickness of the foil in mm?

Answer 1

Answer;

= 0.018 mm

Explanation;

Mass = 12 ounces

1 ounce = 28.4 g

thus mass in g = 12 × 28.4 = 340.8 g

Volume = mass/density

            = 340.8 g /2.70 g/cm³

            = 126 cm³

The thickness from volume and area;

thickness = volume/ area

Area = 75 square ft

1 Square ft = 929.03 square centimeter

   Thickness = 126 cm³/ (75 × 929.03)

                    =  0.001808 cm

but, 1 cm = 10 mm

Therefore;  0.001808 ×10 = 0.01808 mm

  = 0.018 mm ( 3 decimal places)

Answer 2

Solution:

Since we know that 1 ounce=28.4g/oz

So for 12 oz  X  28.4 g/oz  =  340.8 g

And,

 340.8 g  X  1cm3/2.7g  =  126.22 cm3

Again,

75 ft2  X  12 in/ft  X  12 in/ft  X  2.54 cm/in  X  2.54 cm/in  =  69,677.28 cm2  

(Here ft^2=ft*ft)

Now,

69,677.28 cm2  X Thickness  =  126.22 cm3

Finally Solve for Thickness: 126.22 cm3 / 69,677.28 cm2  =  0.00181 cm

Thus for mm we have to:

0.00181 cm  X  10 mm/1 cm  =  0.0181 mm.