Question 1006251: The percent l(x)of the original intensity of light striking the surface of a lake that is available x feet below the surface of the lake is given by the equation
l(x) = 100e^−0.95x.
(a) What percentage of the light, to the nearest tenth of a percent, is available 4 feet below the surface of the lake?
%
(b) At what depth, to the nearest hundredth of a foot, is the intensity of the light one-half the intensity at the surface?
ft
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! L(x)=100e^(-3.8) at 4 feet.
This is 2.2%
I want 50% or 50=100e^(-0.95x)
0.5=e^(-0.95x)
ln of both sides
-0.693=-0.95 x
At 0.73 feet, dividing both sides by -0.95.
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