this is just like the interest problem. If 45% are cleared, then 55% are left.
e^(−0.3821t) = 0.55
Now just solve for t
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 = y0e^(−0.3821t),
where t is the time in years and y0 is the pollutant level at which further pollution ceased. How many years would it take to clear 45% of the pollutants? (Round your answer to three decimal places.)
1 answer