5. The amount Q(t) measured in milligrams of a prescription medica t hours after ingestion is modeled by the equation: Q(t) = 500(.75)* a. What is the rate of decay for this medication? -You body

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### Mathematical Modeling in Pharmacology

#### Problem 5: Medication Decay Over Time

The amount \( Q(t) \) measured in milligrams of a prescription medication that remains in the body \( t \) hours after ingestion is modeled by the equation:

\[ Q(t) = 500 (0.75)^t \]

#### Questions and Solutions:

**a. What is the rate of decay for this medication?**

The decay rate can be determined by understanding the base of the exponential function, \( 0.75 \). 

\[ 0.75 = 1 - 0.25 \]

This shows that the rate of decay is \( 0.25 \) or \( 25\% \).

**b. How much of the medication is left after 6 hours? Round to the nearest thousandth.**

To determine the amount left after 6 hours, substitute \( t = 6 \) into the equation:

\[ Q(6) = 500 (0.75)^6 \]

Calculation:

\[ Q(6) = 500 \times 0.177978515625 \approx 88.989 \]

Therefore, approximately 88.989 milligrams of the medication remain after 6 hours.

**c. A second dose can be administered when there are only 80 milligrams remaining. When does this happen? Round to the nearest tenth.**

We need to solve for \( t \) when \( Q(t) = 80 \):

\[ 80 = 500 (0.75)^t \]

Divide both sides by 500:

\[ \frac{80}{500} = (0.75)^t \]

\[ 0.16 = (0.75)^t \]

Taking the logarithm of both sides:

\[ \log(0.16) = t \log(0.75) \]

\[ t = \frac{\log(0.16)}{\log(0.75)} \]

Calculation:

\[ t \approx \frac{-0.796}{-0.125} \approx 6.4 \]

Therefore, a second dose can be administered after approximately 6.4 hours.
Transcribed Image Text:### Mathematical Modeling in Pharmacology #### Problem 5: Medication Decay Over Time The amount \( Q(t) \) measured in milligrams of a prescription medication that remains in the body \( t \) hours after ingestion is modeled by the equation: \[ Q(t) = 500 (0.75)^t \] #### Questions and Solutions: **a. What is the rate of decay for this medication?** The decay rate can be determined by understanding the base of the exponential function, \( 0.75 \). \[ 0.75 = 1 - 0.25 \] This shows that the rate of decay is \( 0.25 \) or \( 25\% \). **b. How much of the medication is left after 6 hours? Round to the nearest thousandth.** To determine the amount left after 6 hours, substitute \( t = 6 \) into the equation: \[ Q(6) = 500 (0.75)^6 \] Calculation: \[ Q(6) = 500 \times 0.177978515625 \approx 88.989 \] Therefore, approximately 88.989 milligrams of the medication remain after 6 hours. **c. A second dose can be administered when there are only 80 milligrams remaining. When does this happen? Round to the nearest tenth.** We need to solve for \( t \) when \( Q(t) = 80 \): \[ 80 = 500 (0.75)^t \] Divide both sides by 500: \[ \frac{80}{500} = (0.75)^t \] \[ 0.16 = (0.75)^t \] Taking the logarithm of both sides: \[ \log(0.16) = t \log(0.75) \] \[ t = \frac{\log(0.16)}{\log(0.75)} \] Calculation: \[ t \approx \frac{-0.796}{-0.125} \approx 6.4 \] Therefore, a second dose can be administered after approximately 6.4 hours.
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