The amount of light passing through each foot the water in the lake = 100% - 60% = 40%
The percent of light passing through 5 feet of water = 0.4^5 = 0.01024 = 1.02%
This is an exponential function.
If x = 0, 2^x = 2^0 = 1. The beginning value of 2^x is 1 and the beginning value of 51*2^x is 51.
Make a table and graph the points:
x y=51*2^x point (x,y)
-- --------------- ---------------
0 51 (0,51)
2 51*2^2 = 51(4) = 204 (2,204) and so on.
The graph shows up in both Quadrants I and II. Its y-intercept is (0,51). Its slope is always positive.
-3/8x - 11 = 4
-3/8x = 15 Add 11 to both sides
x = -40 Divide both sides by -3/8
