The amount of caffeine in the body of a healthy adult after drinking espresso decreases exponentially, with a half-life of appro
ximately 6 hours. That is, every 6 hours, the amount of caffeine in the body decreases by 50%. Charlotte wants to go to sleep at 11 pm and does not want more than 20 milligrams (mg) of caffeine in her system at that time. What is the latest time Charlotte can drink a 2-ounce shot of espresso that contains 80 mg of caffeine?
A. 5 am
B. 11 am
C. 11:30 am
D. 12 pm
A. 5 am
B. 11 am
C. 11:30 am
D. 12 pm
2 answers:
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You can solve this by making a proportion.
you cross multiply and divide to solve this. your answer is 8.
you cross multiply and divide to solve this. your answer is 8.
Answer:
Step-by-step explanation:
The position function is
and if we are looking for the time(s) that the ball is 10 feet above the surface of the moon, we sub in a 10 for s(t) and solve for t:
and
and factor that however you are currently factoring quadratics in class to get
t = .07 sec and t = 18.45 sec
There are 2 times that the ball passes 10 feet above the surface of the moon, once going up (.07 sec) and then again coming down (18.45 sec).
For part B, we are looking for the time that the ball lands on the surface of the moon. Set the height equal to 0 because the height of something ON the ground is 0:
and factor that to get
t = -.129 sec and t = 18.65 sec
Since time can NEVER be negative, we know that it takes 18.65 seconds after launch for the ball to land on the surface of the moon.