Finding percentage

• Oct 26th 2008, 02:12 PM
dc52789
Finding percentage
Light intensity l relative to depth d (in feet) for one of the clearest bodies of water in the world, the Sargasso Sea in the West Indies, can be approximated by l = l0e^-0.00942d where lo is the intensity of light at the surface. What percentage of the surface light will reach a depth of A) 50 feet B) 100 feet?
• Oct 26th 2008, 04:12 PM
HallsofIvy
Just do the arithmetic! Putting d= 50 and 100 in that formula gives the light intensity as a fraction times the surface light. The "percentage" is just that fraction changed to a percent.
• Oct 26th 2008, 04:14 PM
dc52789
Quote:

Originally Posted by HallsofIvy
Just do the arithmetic! Putting d= 50 and 100 in that formula gives the light intensity as a fraction times the surface light. The "percentage" is just that fraction changed to a percent.

what would that leave l and l0?
• Oct 26th 2008, 05:24 PM
Jhevon
Quote:

Originally Posted by dc52789
what would that leave l and l0?

• Oct 26th 2008, 05:27 PM
dc52789
Quote:

Originally Posted by Jhevon

I'm trying to figure out what the l and lo is?
• Oct 26th 2008, 05:29 PM
Jhevon
Quote:

Originally Posted by dc52789
I'm trying to figure out what the l and lo is?

in that case, HallsofIvy answered your question. just plug in the values. what do you get? you will get that the intensity is some decimal times $I_0$. this decimal will tell you the percentage

you are not required to find the values of $I$ and $I_0$ specifically
• Oct 26th 2008, 05:36 PM
dc52789
Quote:

Originally Posted by Jhevon
in that case, HallsofIvy answered your question. just plug in the values. what do you get? you will get that the intensity is some decimal times $I_0$. this decimal will tell you the percentage

you are not required to find the values of $I$ and $I_0$ specifically

So...do I just do e^(-0.00942x50) and e^(-0.00942x100)?
• Oct 26th 2008, 05:40 PM
Jhevon
Quote:

Originally Posted by dc52789
So...do I just do e^(-0.00942x50) and e^(-0.00942x100)?

yes. and in each case, say what percentage of the surface intensity you have
• Oct 26th 2008, 05:43 PM
dc52789
Quote:

Originally Posted by Jhevon
yes. and in each case, say what percentage of the surface intensity you have

I have A) 0.6244 B) 0.3898
• Oct 26th 2008, 06:05 PM
Here to Help
Convert to a percentage
To convert decimal to percent just multiply by 100.
• Oct 26th 2008, 06:44 PM
dc52789
Quote:

Originally Posted by Here to Help
To convert decimal to percent just multiply by 100.

that would be 62.44% and 38.98%