Question

MEDAL AND FAN
If each foot of water in a lake screens out 60% of the light above, what percent of the light passes through 5 feet of water?
a.
15%
c.
1.024%
b.
25%
d.
3.725%

Answer 1

@D3xt3R help again ;)

Answer 2

@ganeshie8

Answer 3

if the lake screens out 60% of the light above, then 40% pass by it.\[P(h)=0.40^{h}\]\[P(5)=0.40^5\]The correct anser is:\[P(5)=0.01024=1.024\%\]

Answer 4

thnx

Answer 5

any logic behind getting that equation so easily??

Answer 6

Each foot screens out 60% of the light. So 100% - 60% = 40% of the light gets through in the first foot.

Through the second foot of water, 40% of the light that made it through then makes it through to the next layer. So 0.4*0.4 so far

Third foot: 0.4*0.4*0.4

etc etc

Through the 5th foot of water, we'll have 0.4*0.4*0.4*0.4*0.4 = 0.4^5 which is how D3xt3R got that equation

Answer 7

thank u