A culture of bacteria has a population of 150 cells when it is first observed. The population doubles every 12hr, 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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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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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Exponential Growth
Exponential growth occurs when a quantity increases at a rate proportional to its current value. In the context of the bacteria population, the population doubles every 12 hours, which can be modeled by the function p(t) = 150 * 2^(t/12). This type of growth leads to rapid increases over time, making it essential to understand when analyzing population dynamics.
Doubling time is the period it takes for a quantity to double in size. For the bacteria population, the doubling time is given as 12 hours. This concept is crucial for calculating future population sizes and understanding the rate of growth, as it provides a consistent measure of how quickly the population expands.
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Logarithmic Functions
Logarithmic functions are the inverses of exponential functions and are used to solve for time in growth problems. To determine how long it takes for the population to triple, one can set up the equation 3 * 150 = 150 * 2^(t/12) and solve for t using logarithms. This concept is vital for transitioning from exponential growth equations to practical time calculations.