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The Tojolobal Mayan Indian community in southern Mexico has available a fixed amount of land. The proportion, \(P\), of land in use for farming \(t\) years after 1935 is modeled with the logistic function in Figure \(11.75:^{23}$$$P=\frac{1}{1+2.968 e^{-0.0275 t}}$$ (a) What proportion of the land was in use for farming in \)1935 ?$ (b) What is the long-run prediction of this model? (c) When was half the land in use for farming? (d) When is the proportion of land used for farming increasing most rapidly?

Short Answer

Expert verified
(a) 25.2%; (b) 100%; (c) 1973; (d) 1973.

Step by step solution

01

Initial Proportion in 1935

To find the proportion of land in use for farming in 1935, substitute \( t = 0 \) into the logistic function. \[ P = \frac{1}{1 + 2.968 e^{-0.0275 \times 0}} = \frac{1}{1 + 2.968} \] Thus, \[ P = \frac{1}{3.968} \approx 0.252 \]. Therefore, approximately 25.2% of the land was in use.
02

Long-Run Proportion Prediction

The long-run prediction of the logistic model is determined by the limiting behavior as \( t \to \infty \). As \( t \to \infty \), the term \( e^{-0.0275 t} \to 0 \), leading to: \[ P = \frac{1}{1 + 0} = 1 \]. Thus, in the long run, 100% of the land is predicted to be in use.
03

Half the Land in Use

To determine when half the land was in use, set \( P = 0.5 \) and solve for \( t \): \[ 0.5 = \frac{1}{1 + 2.968 e^{-0.0275 t}} \] Solving, we get: \[ 1 + 2.968 e^{-0.0275 t} = 2 \] \[ 2.968 e^{-0.0275 t} = 1 \] \[ e^{-0.0275 t} = \frac{1}{2.968} \approx 0.337 \] Taking the natural log of both sides, \[ -0.0275 t = \ln(0.337) \] \[ t = -\frac{\ln(0.337)}{0.0275} \approx 38.9 \] Therefore, around 1973 (1935 + 39), half the land was in use.
04

Most Rapid Increase

The logistic function increases most rapidly at its inflection point, where \( P = 0.5 \). From Step 3, we found this occurs at approximately \( t = 39 \), or the year 1973. Hence, 1973 is when the proportion of land used for farming was increasing most rapidly.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Land Use Modeling
Land use modeling is an essential technique used to predict and analyze how different portions of land are utilized over time. In the context of the Tojolobal Mayan community, a logistic function is applied to model the proportion of land used for farming from the year 1935 onwards. The logistic function provides an S-shaped curve, which is very useful when the change happens gradually and eventually levels off. Here, the formula \[ P = \frac{1}{1 + 2.968 e^{-0.0275 t}} \]represents this logistic function. The variable \( t \) refers to the number of years after 1935, and the formula helps us understand how land-use evolves over time. The parameters in the equation are critical:
  • The initiator, \( 2.968 \), affects how quickly the process begins.
  • The growth rate,\( -0.0275 \), determines how fast the land transitions into use.
By using such models, communities can effectively plan and allocate resources to ensure sustainable agricultural development. Furthermore, it offers insight into how land usage changes respond to socio-economic and environmental factors.
Long-Run Behavior
The long-run behavior of a logistic function describes what happens as time progresses infinitely. In a logistic model like the one for the Tojolobal Mayan community, the term \( e^{-0.0275 t} \) vanishes as \( t \) grows very large. This simplification leads us to:\[ P = \frac{1}{1 + 0} = 1 \]What does this tell us? It predicts that, in the long run, 100% of the available land will be used for farming. This understanding is crucial for land use planning and management as it provides a clear end-goal or limit. Knowing that all available land will eventually be in use allows for strategies to be crafted that promote sustainable farming practices and avoid potential overuse or degradation. Planners can use this information to assess land resource needs and development priorities in anticipation of future conditions.
Inflection Point
The inflection point in a logistic function is a pivotal moment where the rate of change in land use transitions. It's where the land utilization switches from accelerating to decelerating, making it the stage of maximal growth. For the function modeling land use of the Tojolobal Mayan community, this point occurs where the proportion \( P = 0.5 \). In practical terms, it means that at the inflection point, half of the land suitable for farming is being utilized. By examining this aspect of the model, community planners can recognize a significant period of growth and focus resources and efforts on efficient land management during this time. It aligns with the year 1973, given the calculation from earlier. Understanding and identifying the inflection point help in anticipating critical changes and effectively managing land resources.
Proportion Analysis
Proportion analysis involves examining and interpreting what different proportions of land use signify in a logistic model. In this specific model for the Tojolobal community, significant proportions tell us detailed stories about the land use: - **Initial Proportion:** In 1935, only about 25.2% of the land was in use for farming. This initial condition gives historical context about societal and economic priorities at that time. - **Midpoint Proportion:** As discussed, by 1973 about 50% of the land got used. This marks a dynamic shift and suggests rapid development or changes in agricultural practices. - **Future Proportion:** Looking ahead, the analysis predicts full usage of the land, reflecting the long-run behavior discussed earlier. Through such analysis, stakeholders can obtain a deeper understanding of trends over time, helping them craft more informed policies and interventions targeting land use efficiency and development.

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