Question

An antibiotic loses 15% of its effectiveness in each hour after it has been taken.

The doctor prescribed a 500mg dose; the first dose was taken at 8am.
Construct a model to represent the amount of antibiotic remaining after any
given number of hours, then use your model to determine the amount of
antibiotic that remains at 6:00pm. Round your answer to the nearest tenth of a
milligram.

Answer 1

12.5mg left at 6pm

Explanation:

500mg x 15% = 75mg/hr

Taken at 8am and by 2pm that's 6/hrs 7 x 75mg/hr = 450mg

By 2pm only 50mg are left

Taken at 8am, by 6pm that's 10/hrs

With 50mg left and 4hrs to go

50mg ÷ 4 = 12.5mg