/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 1 The following exponential functi... [FREE SOLUTION] | 91Ó°ÊÓ

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The following exponential functions represent population growth. Identify the initial population and the growth factor. a. \(Q=275 \cdot 3^{T}\) b. \(P=15,000 \cdot 1.04^{t}\) c. \(y=\left(6 \cdot 10^{8}\right) \cdot 5^{x}\) d. \(A=25(1.18)^{t}\) e. \(P(t)=8000(2.718)^{t}\) f. \(f(x)=4 \cdot 10^{5}(2.5)^{x}\)

Short Answer

Expert verified
a. Initial = 275, Growth Factor = 3; b. Initial = 15,000, Growth Factor = 1.04; c. Initial = 600,000,000, Growth Factor = 5; d. Initial = 25, Growth Factor = 1.18; e. Initial = 8,000, Growth Factor = 2.718; f. Initial = 400,000, Growth Factor = 2.5.

Step by step solution

01

- Identify the Initial Population

For exponential functions of the form \(y = a \cdot b^{x}\), the initial population is the coefficient \(a\). Locate this coefficient in each of the functions provided.
02

- Identify the Growth Factor

In an exponential function \(y = a \cdot b^{x}\), the base \(b\) of the exponential term represents the growth factor. Identify this base in each function.
03

- Example Analysis

Using the steps above, analyze each equation separately to find the initial population and growth factor.
04

Step 4a - Analyze Function a

For the function \(Q=275 \cdot 3^{T}\), the initial population is \(275\) and the growth factor is \(3\).
05

Step 4b - Analyze Function b

For the function \(P=15,000 \cdot 1.04^{t}\), the initial population is \(15,000\) and the growth factor is \(1.04\).
06

Step 4c - Analyze Function c

For the function \(y=6 \cdot 10^{8} \cdot 5^{x}\), the initial population is \(6 \cdot 10^{8} = 600,000,000\) and the growth factor is \(5\).
07

Step 4d - Analyze Function d

For the function \(A=25 \cdot 1.18^{t}\), the initial population is \(25\) and the growth factor is \(1.18\).
08

Step 4e - Analyze Function e

For the function \(P(t)=8000 \cdot 2.718^{t}\), the initial population is \(8000\) and the growth factor is \(2.718\).
09

Step 4f - Analyze Function f

For the function \(f(x)=4 \cdot 10^{5} \cdot 2.5^{x}\), the initial population is \(4 \cdot 10^{5} = 400,000\) and the growth factor is \(2.5\).

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Key Concepts

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

Initial Population
In exponential growth models, the initial population refers to the population size at the beginning of the observation period. It is commonly represented by the coefficient in an exponential function of the form \( y = a \times b^x \). Here's a brief breakdown of identifying the initial population in some example functions:
  • For \( Q = 275 \times 3^T \), the initial population is \( 275 \).
  • In the function \( P = 15,000 \times 1.04^t \), the initial population is \( 15,000 \).
  • For \( y = (6 \times 10^8) \times 5^x \), the initial population is \( 6 \times 10^8 \), which is \( 600,000,000 \).
  • In \( A = 25 \times 1.18^t \), the coefficient \( 25 \) is the initial population.
  • For \( P(t) = 8,000 \times 2.718^t \), the initial population is \( 8,000 \).
  • In the function \( f(x) = 4 \times 10^5 \times 2.5^x \), the initial population is \( 4 \times 10^5 \), which equals \( 400,000 \).
Growth Factor
The growth factor in an exponential function determines how rapidly the population increases. This is represented by the base \( b \) in the general form \( y = a \times b^x \). Let's look at some examples:
  • In \( Q = 275 \times 3^T \), the growth factor is \( 3 \).
  • For \( P = 15,000 \times 1.04^t \), the growth factor is \( 1.04 \).
  • In \( y = (6 \times 10^8) \times 5^x \), the growth factor is \( 5 \).
  • For \( A = 25 \times 1.18^t \), the growth factor is \( 1.18 \).
  • In \( P(t) = 8,000 \times 2.718^t \), the growth factor is \( 2.718 \).
  • For \( f(x) = 4 \times 10^5 \times 2.5^x \), the growth factor is \( 2.5 \).
Exponential Functions
Exponential functions are mathematical expressions used to describe processes where quantities grow at rates proportional to their current values. They have a general form of \( y = a \times b^x \), where:
  • \( y \) is the dependent variable (e.g., population size).
  • \( a \) is the initial value (initial population).
  • \( b \) is the growth factor.
  • \( x \) is the independent variable (often representing time).
Exponential functions are used in various fields such as biology, finance, and physics to model phenomena that exhibit rapid growth or decay.
Algebraic Functions
While exponential functions deal with rapidly growing or decaying quantities, algebraic functions involve polynomial expressions where variables are raised to whole number powers. For instance, a quadratic function like \( y = ax^2 + bx + c \) is an algebraic function. These functions often depict slower, more gradual changes compared to exponential growth. Understanding the key differences between algebraic and exponential functions is crucial for proper application in problem-solving and population modeling.
Population Modeling
Population modeling involves the use of mathematical functions to represent how populations change over time. Exponential growth models are especially common in scenarios where a population grows without significant constraints. The general form \( y = a \times b^x \) provides a straightforward means of predicting future population sizes based on current growth trends.
  • Initial population \( a \) sets the starting point for the model.
  • Growth factor \( b \) influences the rate of increase.
These models help in various fields, including ecology, economics, and social sciences, to make informed decisions based on predicted population trends.

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Most popular questions from this chapter

Identify the doubling time or half-life of each of the following exponential functions. Assume \(t\) is in years. [Hint: What value of \(t\) would give you a growth (or decay) factor of 2 (or \(1 / 2\) )?] a. \(Q=70(2)^{t}\) b. \(Q=1000(2)^{t / 50}\) c. \(Q=300\left(\frac{1}{2}\right)^{t}\) d. \(Q=100\left(\frac{1}{2}\right)^{t / 250}\) e. \(N=550(2)^{t / 10}\) f. \(N=50\left(\frac{1}{2}\right)^{t / 20}\)

Two cities each have a population of 1.2 million people. City A is growing by a factor of 1.15 every 10 years, while city \(\mathbf{B}\) is decaying by a factor of 0.85 every 10 years. a. Write an exponential function for each city's population \(P_{A}(t)\) and \(P_{B}(t)\) after \(t\) years. b. For each city's population function generate a table of values for \(x=0\) to \(x=50,\) using 10 -year intervals, then sketch a graph of each town's population on the same grid.

(Graphing program recommended.) On the same graph, sketch \(f(x)=3(1.5)^{x}, g(x)=-3(1.5)^{x},\) and \(h(x)=3(1.5)^{-x}\) a. Which graphs are mirror images of each other across the \(y\) -axis? b. Which graphs are mirror images of each other across the \(x\) -axis? c. Which graphs are mirror images of each other about the origin (i.e., you could translate one into the other by reflecting first about the \(y\) -axis, then about the \(x\) -axis)? d. What can you conclude about the graphs of the two functions \(f(x)=C a^{x}\) and \(g(x)=-C a^{x} ?\) e. What can you conclude about the graphs of the two functions \(f(x)=C a^{x}\) and \(g(x)=C a^{-x} ?\)

In a chain letter one person writes a letter to a number of other people, \(N,\) who are each requested to send the letter to \(N\) other people, and so on. In a simple case with \(N=2\), let's assume person Al starts the process. Al sends to \(\mathrm{B} 1\) and \(\mathrm{B} 2 ; \mathrm{B} 1\) sends to \(\mathrm{C} 1\) and \(\mathrm{C} 2 ; \mathrm{B} 2\) sends to \(\mathrm{C} 3\) and \(\mathrm{C} 4\); and so on. A typical letter has listed in order the chain of senders who sent the letters. So \(\mathrm{D} 7\) receives a letter that has \(\mathrm{A} 1, \mathrm{~B} 2\), and \(\mathrm{C} 4\) listed. If these letters request money, they are illegal. A typical request looks like this: \(\cdot\) When you receive this letter, send \(\$ 10\) to the person on the top of the list. \(\cdot\) Copy this letter, but add your name to the bottom of the list and leave off the name at the top of the list. \(\cdot\) Send a copy to two friends within 3 days. For this problem, assume that all of the above conditions hold. a. Construct a mathematical model for the number of new people receiving letters at each level \(L,\) assuming \(N=2\) as shown in the above tree. b. If the chain is not broken, how much money should an individual receive? c. Suppose A 1 sent out letters with two additional phony names on the list (say Ala and Alb) with P.O. box addresses she owns. So both \(\mathrm{B} 1\) and \(\mathrm{B} 2\) would receive a letter with the list \(\mathrm{A} 1, \mathrm{~A} 1 \mathrm{a},\) Alb. If the chain isn't broken, how much money would Al receive? d. If the chain continued as described in part (a), how many new people would receive letters at level \(25 ?\) e. Internet search: Chain letters are an example of a "pyramid growth" scheme. A similar business strategy is multilevel marketing. This marketing method uses the customers to sell the product by giving them a financial incentive to promote the product to potential customers or potential salespeople for the product. (See Exercise \(31 .)\) Sometimes the distinction between multilevel marketing and chain letters gets blurred. Search the U.S. Postal Service website (www.usps.gov) for "pyramid schemes" to find information about what is legal and what is not. Report what you find.

Each table has values representing either linear or exponential functions. Find the equation for each function. $$ \begin{array}{cccccc} \hline x & -2 & -1 & 0 & 1 & 2 \\ h(x) & 160 & 180 & 200 & 220 & 240 \\ \hline \end{array} $$ $$ \begin{aligned} &\text { b. }\\\ &\begin{array}{cccccc} \hline x & 0 & 10 & 20 & 30 & 40 \\ j(x) & 200 & 230 & 264.5 & 304.17 & 349.8 \\ \hline \end{array} \end{aligned} $$

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