Answer:
The rate of decay is: 

Explanation:
Exponential functions are modeled by:

Where 
 is the y-intercept and b is the growth or decay constant. If
 is the y-intercept and b is the growth or decay constant. If 
 is less than one, the function decays. If
 is less than one, the function decays. If 
 is greater than 1, the function grows.
 is greater than 1, the function grows.
To calculate the percentage, subtract 
 from 1:
 from 1:

Multiply the result by 100 to get the percentage.
