At time t hours after taking the cough suppressant hydrocodone bitartrate, the amount, A, in mg, remaining in the body is given by A = 12(0.9). (a) What was the initial amount taken? 12 mg (b) What percent of the drug leaves the body each hour? Decimal form: % (c) Find the time until only 1 mg of the drug remains in the body. Give your answer in exact form and decimal form. Exact form: hours hours (nearest tenth)

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Author:James Stewart
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### Drug Decay Model: Hydrocodone Bitartrate

At time \( t \) hours after taking the cough suppressant hydrocodone bitartrate, the amount, \( A \) in mg, remaining in the body is given by the equation: 

\[ A = 12(0.9)^t \]

#### Question (a)
**What was the initial amount taken?**

*Answer:*
[ ✔ ] \( \boxed{12} \) mg

#### Question (b)
**What percent of the drug leaves the body each hour?**

*Answer:*
[ ✘ ] (This answer was not provided)

#### Question (c)
**Find the time until only 1 mg of the drug remains in the body. Give your answer in exact form and decimal form.**

*Answer:*

- **Exact form:** [               ] hours
- **Decimal form:** [           ] hours (nearest tenth)

---

#### Explanation of the Equation and Process:
1. **Recognizing Initial Amount:**
   - From the equation \( A = 12(0.9)^t \), the initial amount \( A \) when \( t=0 \) is \( 12 \) mg.

2. **Percent Decay per Hour:**
   - The base of the exponential, \( 0.9 \), indicates that 90% of the drug remains each hour.
   - Therefore, \( 100\% - 90\% = 10\% \) of the drug leaves the body every hour.
   
3. **Solving for Time when 1 mg Remains:**
   - To find the time \( t \) when \( A = 1 \) mg:
     \[
     1 = 12(0.9)^t
     \]
     Divide both sides by 12:
     \[
     (0.0833) = (0.9)^t
     \]
     Taking the natural logarithm of both sides:
     \[
     \ln(0.0833) = t \ln(0.9)
     \]
     Solving for \( t \):
     \[
     t = \frac{\ln(0.0833)}{\ln(0.9)}
     \]

The exact and decimal form answers can be calculated using a scientific calculator or natural logarithm tables. 

---
Transcribed Image Text:--- ### Drug Decay Model: Hydrocodone Bitartrate At time \( t \) hours after taking the cough suppressant hydrocodone bitartrate, the amount, \( A \) in mg, remaining in the body is given by the equation: \[ A = 12(0.9)^t \] #### Question (a) **What was the initial amount taken?** *Answer:* [ ✔ ] \( \boxed{12} \) mg #### Question (b) **What percent of the drug leaves the body each hour?** *Answer:* [ ✘ ] (This answer was not provided) #### Question (c) **Find the time until only 1 mg of the drug remains in the body. Give your answer in exact form and decimal form.** *Answer:* - **Exact form:** [ ] hours - **Decimal form:** [ ] hours (nearest tenth) --- #### Explanation of the Equation and Process: 1. **Recognizing Initial Amount:** - From the equation \( A = 12(0.9)^t \), the initial amount \( A \) when \( t=0 \) is \( 12 \) mg. 2. **Percent Decay per Hour:** - The base of the exponential, \( 0.9 \), indicates that 90% of the drug remains each hour. - Therefore, \( 100\% - 90\% = 10\% \) of the drug leaves the body every hour. 3. **Solving for Time when 1 mg Remains:** - To find the time \( t \) when \( A = 1 \) mg: \[ 1 = 12(0.9)^t \] Divide both sides by 12: \[ (0.0833) = (0.9)^t \] Taking the natural logarithm of both sides: \[ \ln(0.0833) = t \ln(0.9) \] Solving for \( t \): \[ t = \frac{\ln(0.0833)}{\ln(0.9)} \] The exact and decimal form answers can be calculated using a scientific calculator or natural logarithm tables. ---
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