Thread: Finding percentage

1. 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?

2. 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.

3. 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?

4. Originally Posted by dc52789
what would that leave l and l0?
i don't get your question

5. Originally Posted by Jhevon
i don't get your question
I'm trying to figure out what the l and lo is?

6. 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 $\displaystyle I_0$. this decimal will tell you the percentage

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

7. 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 $\displaystyle I_0$. this decimal will tell you the percentage

you are not required to find the values of $\displaystyle I$ and $\displaystyle I_0$ specifically
So...do I just do e^(-0.00942x50) and e^(-0.00942x100)?

8. 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

9. 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

10. Convert to a percentage

To convert decimal to percent just multiply by 100.

11. Originally Posted by Here to Help
To convert decimal to percent just multiply by 100.
that would be 62.44% and 38.98%