Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
0. Functions
Exponential Functions
Problem 1.82d
Textbook Question
A culture of bacteria has a population of 150 cells when it is first observed. The population doubles every 12 hr, which means its population is governed by the function p(t)=150⋅212t, where t is the number of hours after the first observation.
How long does it take the population to triple in size?
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1
Identify the initial population and the function governing the population growth. The initial population is 150 cells, and the function is given by \( p(t) = 150 \cdot 2^{\frac{t}{12}} \).
Determine the target population size for the bacteria to triple. Since the initial population is 150, the target population is \( 3 \times 150 = 450 \) cells.
Set up the equation to find the time \( t \) when the population reaches 450 cells: \( 450 = 150 \cdot 2^{\frac{t}{12}} \).
Divide both sides of the equation by 150 to isolate the exponential term: \( 3 = 2^{\frac{t}{12}} \).
Take the logarithm of both sides to solve for \( t \). Use the property of logarithms that \( \log(a^b) = b \cdot \log(a) \): \( \log(3) = \frac{t}{12} \cdot \log(2) \). Solve for \( t \) by multiplying both sides by 12 and dividing by \( \log(2) \).
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