Answer:
the number of caffeine still in his system by 9:00 am is 192 mg.
Step-by-step explanation:
given information
the mass of initial caffein, m₁ = 300 mg
time, t = 9 - 6 = 2 hours
metabolised = 18%/hour = 0.18/h = 0.18 x 300 mg = 54 mg/h
the student metabolised the caffeine 54 mg/h. thus from 6 am to 9 am the caffeine metabolised is
metabolised in 2 hr = 2 x 54
= 108 mg
the remaining caffeine = initial caffeine - metabolised caffeine
= 300 - 108
= 192 mg
Answer:
The correct answer is 138 mg.
Step-by-step explanation:
To understand this problem we must first analyze it.
We know that the student's body metabolizes 18% of the caffeine ingested every hour.
Therefore we can solve that percentage to already have the number of metabolized caffeine per hour:
(300. 18): 100 =
5400: 100 = 54 mg
We now know that the student's body will metabolize 54 mg of caffeine per hour.
The question is much caffeine is still in his system by 9:00 am?
From 6:00 am to 9:00 am we have 3 hours of difference: 3 . 54 = 162
In three hours 162 mg of caffeine were already processed by his body, therefore, it still needs to be metabolized: 300 - 162 = 138 mg.
