You drink a beverage with 120 mg of caffeine. Each hour, the caffeine in your system decreases by about 12%. How much caffeine is left in your system after 4 hours?

Since the amount if Caffeine decreases by 12% an hour, that is the same as a multiplier of 0.88 per hour.

r = ln 0.88 = -0.117833371

10 = 120 e^-0.117833371t

10/120 =  e^-0.117833371t

0.8333 = 10/120

ln0.8333 = -2.48490665  so

e^-2.48490665 = e^-0.117833371t    and so

-2.48490665 = -0.117833371t

-2.48490665/-0.117833371 = t

21.08830995 hrs = t

thus 21 hrs is your best answer.

10 b/c 5*2 =10

step-by-step explanation: