Answer:
y = 0.01·(0.5^x)
Explanation:
You want the exponential function that gives the sequence ...
0.01 (for x=0), 0.005, 0.0025, 0.00125
Exponential function
The exponential function can be written ...
y = initial value · (common ratio)^x
The initial value is 0.01. The common ratio is 0.005/0.010 = 0.5.
Using these values in the equation, we have ...
y = 0.01(0.5^x)