Question

A patient ingests 100 milligrams of a certain drug which dissolves away at a constant rate of 20% per hour. How long will it take before there are only ten milligrams left?

Answer 1

Answer:

Answer:

The correct answer is 15.3 hours

Step-by-step explanation:

See the attached image below to understand why this is correct.

Answer 2

100×20%=20mg is dissolved in one hour

20mg will be dissolved away which mean it will take 4 hours for 80mg to dissolve way

since it takes 20mg 1hour it will take 10mg half and hour or 30min to dissolve away which gives us a total of 4.5 hrs to dissolve 90mg away and leave us with 10mg