Posted by ##000000 on .
A cup of coffee contains about 100mg caffeine. The exponential function A(t)=100(0.84)^t is used to calculate the amount of caffeine in a body t hours after the coffee was consumed. Find the amount of caffeine in the body after 4 hours. Can someone help with a step by step break down?

Algebra 
Steve,
yeah. plug in the value for t and use your calculator:
A(4) = 100(0.84)^4 = 100*0.5 = 50.0