/*! 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 4 A biologist has discovered that ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

A biologist has discovered that the weight of a certain fish is a power function of its length. He also knows that when the length of the fish is doubled, its weight increases by a factor of 8 . What is the power \(k\) ?

Short Answer

Expert verified
The power \( k \) is 3.

Step by step solution

01

Identify Power Function Relationship

The weight of the fish is related to its length by a power function, which can be expressed generally as \( W = aL^k \), where \( W \) is the weight, \( L \) is the length, \( a \) is a constant, and \( k \) is the power we need to find.
02

Set Up Given Condition

According to the problem, when the fish's length is doubled, its weight increases by a factor of 8. This can be mathematically expressed as: \( a(2L)^k = 8 imes aL^k \).
03

Simplify the Equation

Substitute \( (2L)^k \) with \( 2^kL^k \) in the equation to get \( a imes 2^k imes L^k = 8 imes aL^k \).
04

Cancel Constants and Terms

Since both sides of the equation have \( aL^k \), we can cancel these out, simplifying the equation to \( 2^k = 8 \).
05

Solve for k

Recognize that 8 can be expressed as a power of 2: \( 8 = 2^3 \). So the equation \( 2^k = 2^3 \) implies that \( k = 3 \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Power Law
The power law is a foundational concept in mathematics, indicating the relationship between two quantities where one quantity varies as a power of another. In simpler terms, a power function can describe how one quantity depends on another raised to a certain power. For instance, in the study of the fish, the equation \( W = aL^k \) describes how the weight \( W \) of the fish changes with its length \( L \). Here, \( a \) represents a constant specific to the conditions of the fish, and \( k \) is the power exponent that defines the relationship's nature.

In many scientific observations, power laws help model phenomena where one quantity grows or shrinks at a rate proportional to its current size raised to a power. These are seen in biological studies, such as growth patterns of organisms, or in physics and demographics. It helps predict how changing one variable impacts another, providing a simple yet powerful tool in understanding complex relationships.
  • Power laws reveal fundamental characteristics of relationships.
  • They help predict behavior under variable changes.
  • They are widely applicable across different scientific fields.
Exponents
Exponents are a key mathematical concept that indicate how many times a number, known as the base, is multiplied by itself. In our exercise, the exponent is represented by \( k \) in the equation \( W = aL^k \). This exponent tells us the rate at which the dependent variable (weight) increases as the independent variable (length) is changed.

For example, an exponent of 3 means that if you double the length, the weight increases by 2 raised to the power of 3, which results in an eightfold increase. This is because \((2^3 = 8)\), illustrating how quickly quantities can grow under power functions.
  • Exponents determine the rate of change.
  • They simplify the representation of repeated multiplication.
  • They are crucial for modeling exponential growth.

In everyday applications, exponents help in calculating compounded interest, understanding population growth, and even in managing computer algorithms. The simplistic nature of exponents makes them an essential part of mathematical literacy.
Algebraic Equations
Algebraic equations form the basis for solving mathematical problems, allowing us to formulate relationships between different variables. By expressing relationships algebraically, as seen in the fish weight problem, \( a(2L)^k = 8 \times aL^k \), we translate tangible scenarios into solvable equations.

When dealing with power functions, simplifying the equations accurately is essential. Here, the equation is simplified by replacing \((2L)^k\) with \(2^kL^k\), leading to \(a \times 2^k \times L^k = 8 \times aL^k\). Algebraic manipulation, such as canceling out similar terms and solving for the unknown, \( k \), brings us to the conclusion.
  • Equations translate real-world problems into mathematical form.
  • They provide a structured way to find unknowns.
  • Understanding algebraic manipulations aids problem-solving.

Algebra isn't just about solving equations; it's about understanding patterns and developing analytical skills. Whether applied in engineering, economics, or personal finances, algebraic thinking helps to uncover answers efficiently and effectively.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

This is a continuation of Exercise 5. Table \(5.4\) gives the length \(L\), in inches, of a swimming animal and its maximum speed \(S\), in feet per second, when it swims. a. Find a formula for the regression line of \(\ln S\) against \(\ln L\). (Round the slope to one decimal place.) b. Find a formula that models \(S\) as a power function of \(L\). On the basis of the power you found, what special type of power function is this? $$ \begin{array}{|l|c|c|} \hline \text { Animal } & \text { Length } L & \begin{array}{c} \text { Swimming } \\ \text { speed } S \end{array} \\ \hline \text { Bacillus } & 9.8 \times 10^{-5} & 4.9 \times 10^{-5} \\ \hline \text { Paramecium } & 0.0087 & 0.0033 \\ \hline \text { Water mite } & 0.051 & 0.013 \\ \hline \text { Flatfish larva } & 0.37 & 0.38 \\ \hline \text { Goldfish } & 2.8 & 2.5 \\ \hline \text { Dace } & 5.9 & 5.7 \\ \hline \text { Adélie penguin } & 30 & 12.5 \\ \hline \text { Dolphin } & 87 & 33.8 \\ \hline \end{array} $$ c. Add the graph of \(S\) against \(L\) to the graph of \(F\) that you drew in Exercise \(5 .\) d. Is flying a significant improvement over swimming if an animal is 1 foot long (the approximate length of a flying fish)? e. Would flying be a significant improvement over swimming for an animal 20 feet long? f. A blue whale is about 85 feet long, and its maximum speed swimming is about 34 feet per second. Judging on the basis of these facts, do you think the trend you found in part b continues indefinitely as the length increases?

Ecologists have studied how a population's intrinsic exponential growth rate \(r\) is related to the body weight \(W\) for herbivorous mammals. \({ }^{26}\) In Table \(5.2, W\) is the adult weight measured in pounds, and \(r\) is growth rate per year. $$ \begin{array}{|l|c|c|} \hline \text { Animal } & \text { Weight } W & r \\ \hline \text { Short-tailed vole } & 0.07 & 4.56 \\ \hline \text { Norway rat } & 0.7 & 3.91 \\ \hline \text { Roe deer } & 55 & 0.23 \\ \hline \text { White-tailed deer } & 165 & 0.55 \\ \hline \text { American elk } & 595 & 0.27 \\ \hline \text { African elephant } & 8160 & 0.06 \\ \hline \end{array} $$ a. Make a plot of \(\ln r\) against \(\ln W\). Is it reasonable to model \(r\) as a power function of \(W\) ? b. Find a formula that models \(r\) as a power function of \(W\), and draw a graph of this function.

The yearly inventory expense \(E\), in dollars, of a car dealer is a function of the number \(Q\) of automobiles ordered at a time from the manufacturer. A dealer who orders only a few automobiles at a time will have the expense of placing several orders, whereas if the order sizes are large, then the dealer will have a large inventory of unsold automobiles. For one dealer the formula is $$ E=\frac{425 Q^{2}+8000}{Q}, $$ so \(E\) is a rational function of \(Q\). a. Make a graph of \(E\) versus \(Q\) covering order sizes up to \(10 .\) b. Explain in practical terms the behavior of the graph near the pole at \(Q=0\). (Hint: Keep in mind that there is a fixed cost of processing each order, regardless of the size of the order.)

Poiseuillé's law describes the velocities of fluids flowing in a tube-for example, the flow of blood in a vein. (See Figure 5.104.) This law applies when the velocities are not too large-more specifically, when the flow has no turbulence. In this case the flow is laminar, which means that the paths of the flow are all parallel to the tube walls. The law states that $$ v=k\left(R^{2}-r^{2}\right), $$ where \(v\) is the velocity, \(k\) is a constant (which depends on the fluid, the tube, and the units used for measurement), \(R\) is the radius of the tube, and \(r\) is the distance from the centerline of the tube. Since \(k\) and \(R\) are fixed for any application, \(v\) is a function of \(r\) alone, and the formula gives the velocity at a point of distance \(r\) from the centerline of the tube. a. What is \(r\) for a point along the walls of the tube? What is the velocity of the fluid along the walls of the tube? b. Where in the tube does the fluid flow most rapidly? c. Choose numbers for \(k\) and \(R\) and make a graph of \(v\) as a function of \(r\). Be sure that the horizontal span for \(r\) goes from 0 to \(R\). d. Describe your graph from part c. e. Explain why you needed to use a horizontal span from 0 to \(R\) in order to describe the flow throughout the tube.

Suppose a certain population is initially absent from a certain area but begins migrating there at a rate of \(v\) individuals per day. Suppose further that this is an animal group that would normally grow at an exponential rate. Then the population after \(t\) days in the new area is given by $$ N=\frac{v}{r}\left(e^{r t}-1\right), $$ where \(r\) is a constant that depends on the species and the environment. If the new location proves unfavorable, then the value of \(r\) may be negative. In such a case, we can rewrite the population function as $$ N=\frac{v}{r}\left(a^{t}-1\right), $$ where \(a\) is less than 1. Under these conditions, what is the limiting value of the population?

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.