Sonia has a big test tomorrow and she hasn't started studying. It is 5pm now and she drinks a
deluxe sized coffee with 200 mg of caffeine. The average half life of caffeine is 6 hours, meaning
that every 6 hours the amount of caffeine in her systems reduces by 50%. How many milligrams
of caffeine will be in her system by 4am? Round your answer to the nearest tenth of a mg.