Question

Can someone help me with this Exponential Growth and Decay word problem? I have been able to get the rest of them done but this one stumps me...

Answer 1

A) 61.68

Explanation:

This is an exponential decay of 0.875. The way to know that is to get that is
`(right)/(left) \\` (Pick a random number and divide by the number to the left of it) From there, there is a 12 hour difference from 7 am to 7pm! Divide 306.25/0.875 and divide it by 0.875 by the answer of that each time 12 times. The exact answer is 61.68402914

Answer 2

Answer: option A is the correct answer.

Explanation:

Looking at the table, the amount of medicine in her system is decreasing constantly with time. This constant amount by which this amount of medicine is decreasing is the decay constant.

Decay constant = 350/400 = 306.25/ 350 = 0.875

Let y represent the amount of medicine in her system after t hours.

Let a represent the initial amount of medicine in her system.

Let b represent the decay constant.

Let t represent the number of hours. Therefore, the function representing the exponential decay would be

y = 400b^t

When she wakes up at 7.00 am, the time from 5.00 pm would be 14 hours. Therefore

y = 400 × 0.875^14

y = 61.7 mg