If the Pollution of Lake Erie Were Stopped Suddenly, It

Multiple Choice

If the pollution of Lake Erie were stopped suddenly, it has been estimated that the level y of pollutants would decrease according to the formula y = y _o e ^-0.3937t , where t is the time in years and y _o is the pollutant level at which further pollution ceased. How many years would it take to clear 59% of the pollutants?

A) t = 0.58 years
B) t = 1.34 years
C) t = 2.02 years
D) t = 0.98 years
E) t = 2.26 years