Question

A veterinarian has to give antibiotics to a dog with a leg infection. The dog is given 200 mg, and the antibiotic decays at a rate of 25 percent every 4 hours. What amount of medicine is left in the dog after 16 hours?(1 point)
Responses

0.78 mg
0.78 mg

63.3 mg
63.3 mg

2 mg
2 mg

488.28 mg

Answer 1

After each 4-hour period the dog has 0.75 of the previous amount. In 16 hours there are 4 such periods, so:

Amount = 200 × 0.75^4 = 200 × 0.31640625 = 63.28125 mg ≈ 63.3 mg.