After a large number of drinks, a person has a blood alcohol level of 200 mg/dL (milligrams per deciliter). If the amount of alcohol in the blood decays exponentially, and after2 hours,84.5mg/dLremain, find an exponential model for the person's blood alcohol levelf(t) wheretis the time in hours.

f(t) =

Use your model to estimate the person's blood alcohol level after4hours.(Round your answer to one decimal place.)

mg/dL=