Answer: There were 469,532 American prison for drug related offenses in 2015.
Explanation:
Since we have given that
Number of Americans in prison for drug related offenses in 1980 = 40,900
Rate of increment in Americans in prison from 1980 to 2015 = 1048%
So, Number of Americans who were in prison for drug related offenses in 2015 is given by

Hence, there were 469,532 American prison for drug related offenses in 2015.