Common Core: High School - Functions : Growth and Decay by Contant Percent Rate: CCSS.Math.Content.HSF-LE.A.1c

Study concepts, example questions & explanations for Common Core: High School - Functions

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All Common Core: High School - Functions Resources

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Example Questions

Example Question #31 : Linear, Quadratic, & Exponential Models*

An particular medicine, has a half-life of about \(\displaystyle 4\) hours. If a patient was administered \(\displaystyle $600 mg\) of the drug at \(\displaystyle $9:00 am\), how much is left at \(\displaystyle $2:00 pm\)?

Note: The half life formula is 

\(\displaystyle A=A_0\cdot \left(\frac{1}{2}\right)^{\frac{t}{h}}\)

Possible Answers:

\(\displaystyle A=250.24\textup{ mg}\)

\(\displaystyle A=252.44\textup{ mg}\)

\(\displaystyle A=252.24\textup{ mg}\)

\(\displaystyle A=254.24\textup{ mg}\)

\(\displaystyle A=251.24\textup{ mg}\)

Correct answer:

\(\displaystyle A=252.24\textup{ mg}\)

Explanation:

This question is testing one's ability to recognize real life situations that have a exponential growth or decay over a certain interval and how to deal with them in function form.

For the purpose of Common Core Standards, recognize situations that have a exponential growth or decay over a certain interval, falls within the Cluster A of construct and compare linear, quadratic, and exponential model and solve problems concept (CCSS.Math.content.HSF.LE.A).

Knowing the standard and the concept for which it relates to, we can now do the step-by-step process to solve the problem in question.

Step 1: Identify the known values given in the question.

\(\displaystyle A=A_0\cdot \left(\frac{1}{2}\right)^{\frac{t}{h}}\)

\(\displaystyle \\A_0=\textup{Intial Amount}=600\textup{ mg} \\h=\textup{half life}=4\textup{ hours} \\t_f=2:00\textup{ pm} \\t_i=9:00\textup{ am} \\A=?\)

Step 2: Calculate \(\displaystyle t\).

\(\displaystyle 2:00-9:00\rightarrow 5 \textup{ hours }\)

Step 3: Substitute in known values into the half life formula to solve for \(\displaystyle A\).

\(\displaystyle A=600\textup{ mg}\cdot \left(\frac{1}{2}\right)^{\frac{5}{4}}\)

\(\displaystyle A=600\textup{ mg}\cdot \left(\frac{1}{2}\right)^{1.25}\)

\(\displaystyle A=600\textup{ mg}\cdot 0.4204\)

\(\displaystyle A=252.24\textup{ mg}\)

Example Question #32 : Linear, Quadratic, & Exponential Models*

An particular medicine, has a half-life of about \(\displaystyle 5.8\) hours. If a patient was administered \(\displaystyle $400 mg\) of the drug at \(\displaystyle $9:00 am\), how much is left at \(\displaystyle $2:00 pm\)?

Note: The half life formula is 

\(\displaystyle A=A_0\cdot \left(\frac{1}{2}\right)^{\frac{t}{h}}\)

Possible Answers:

\(\displaystyle A=220.08\textup{ mg}\)

\(\displaystyle A=222.08\textup{ mg}\)

\(\displaystyle A=210.08\textup{ mg}\)

\(\displaystyle A=228.02\textup{ mg}\)

\(\displaystyle A=218.18\textup{ mg}\)

Correct answer:

\(\displaystyle A=220.08\textup{ mg}\)

Explanation:

This question is testing one's ability to recognize real life situations that have a exponential growth or decay over a certain interval and how to deal with them in function form.

For the purpose of Common Core Standards, recognize situations that have a exponential growth or decay over a certain interval, falls within the Cluster A of construct and compare linear, quadratic, and exponential model and solve problems concept (CCSS.Math.content.HSF.LE.A).

Knowing the standard and the concept for which it relates to, we can now do the step-by-step process to solve the problem in question.

Step 1: Identify the known values given in the question.

\(\displaystyle A=A_0\cdot \left(\frac{1}{2}\right)^{\frac{t}{h}}\)

\(\displaystyle \\A_0=\textup{Intial Amount}=400\textup{ mg} \\h=\textup{half life}=5.8\textup{ hours} \\t_f=2:00\textup{ pm} \\t_i=9:00\textup{ am} \\A=?\)

Step 2: Calculate \(\displaystyle t\).

\(\displaystyle 2:00-9:00\rightarrow 5 \textup{ hours }\)

Step 3: Substitute in known values into the half life formula to solve for \(\displaystyle A\).

\(\displaystyle A=400\textup{ mg}\cdot \left(\frac{1}{2}\right)^{\frac{5}{5.8}}\)

\(\displaystyle A=400\textup{ mg}\cdot \left(\frac{1}{2}\right)^{0.8621}\)

\(\displaystyle A=400\textup{ mg}\cdot 0.5502\)

\(\displaystyle A=220.08\textup{ mg}\)

All Common Core: High School - Functions Resources

6 Diagnostic Tests 82 Practice Tests Question of the Day Flashcards Learn by Concept
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