Thursday, May 13, 2010

Square Feet of Skin

I taught one of my math classes yesterday and in the textbook was this application problem with the formula to figure out how much skin you have on your body (how cool is that?? or am i letting my nerd flag fly again?). I wanted so badly to have them figure out how much skin I have hanging on my shrunken body bu I figured that was one of those TMI kinds of things. My students have only ever known me at this weight. It is weird that I am now thinking of people who knew me fat and those who have never known me at my old size. Anyway---back to the math :)

Here is the problem:

3. Area of skin: The surface are of the skin covering the human body is a function of more than one variable. Both height and weight influence the surface area of a person’s body. Hence a taller person tends to have a larger surface area, as does a heavier person. A formula to determine the area of a person’s skin in square inches is S=15.7w^0.425 h^0.725 Where w is weight in pounds and h is height in inches. (from intermediate Algebra by Rockswold and Krieger)

I of course will want to know how much skin I have hanging on my now smaller frame. My math gives me this:

S=15.7w^0.425 h^0.725
S=3799.165 square inches of skin
If I divide this by 144 I can convert the number to square feet: 26.38 square feet of skin
At my new weight the number 304 should be changed to 189.2 (as of scale this morning). More calculations gives me: S=3105.66 square inches of skin or 21.57 square feet of skin.

Ok so… If my skin did not shrink at all from my highest weight I have 26.38 square feet of skin hanging on a body that should have 21.57. That is an extra 4.81 feet of skin. Given my saggy arms, chin, stomach and legs I believe it.
I wonder how much skin shrinkage a 46 year old woman gets?

Just as my class was ready to go I challenged them look at the tiles in the hallway (1 foot by 1 foot) to see what a bear skin type rug of their skin would look like. Mine is almost as big as the area rug in my family room!!


Fiona said...

OMG I nearly broke out in a sweat reading your blog. I am petrified of math. But skin is also a scary subject and I think even if I could work it out I would rather not know. Now you know, do you think ignorance is bliss?

Justine said...

I kind of want to know, but I also kind of don't. Talking of skin in this way makes me think of Silence of the Lambs! EEEEK!

Nella said...

you lost me at Algebra!
Can you come to Vancouver and calculate mine??

Tina said...

Actually Fiona I have a bit of a sick sense of humor so I kind of like the knowledge.

Justine-I thought of silence of the lambs too. My college age students liked the problem too...and they thought of the movie especially when i brought up comparing it to the tiles in the hallway.

One of my students interested in nursing informed us that our skin is our biggest organ.