In 2007 the initial amount of a radioactive substance is 100
In 2007 the initial amount of a radioactive substance is 100 grans and is decreasing exponentially at a yearly rate of 9% 
 A. Find the amount of the radioactive substance in the year 2023
 B. In what year will there be half of the substance left
 In 2007 the initial amount of a radioactive substance is 100 grans and is decreasing exponentially at a yearly rate of 9% 
 A. Find the amount of the radioactive substance in the year 2023
 B. In what year will there be half of the substance left
 A. Find the amount of the radioactive substance in the year 2023
 B. In what year will there be half of the substance left
Solution
No = 100
r = 0.09
Then function will be N = No*e^(-0.09*t)
A) t = 16
N = 100*e^(-0.09*16) = 23.7 grams
B) 0.5 = e^(-0.09*t) =====> t = 7.7 years
In 2014 it will be half.

