Reminder Round all answers to two decimal places unless otherwise indicated.
Magnitude and Energy The magnitude
Here the unit of energy is the terajoule, which is one trillion joules. One joule is approximately the energy expended in lifting
a.What is the magnitude of a
b.On September 24, 2013, a quake of magnitude
c.The atomic bomb dropped on Hiroshima released about
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Chapter 4 Solutions
Functions and Change: A Modeling Approach to College Algebra (MindTap Course List)
- Reminder Round all answers to two decimal places unless otherwise indicated. The pH Scale Acidity of a solution is determined by the concentration H of hydrogen ions in the solution measured in moles per liter of solution. Chemists use the negative of the logarithm of the concentration of hydrogen ions to define the pH scale: pH=logH Lower pH values indicate a more acidic solution. a.Normal rain has a pH value of 5.6. Rain in the eastern United States often has a pH level of 3.8. How much more acidic is this than normal rain? b.If the pH of water in lake falls below a value of 5, fish often fail to reproduce. How much more acidic is this than normal water with a pH of 5.6?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Gross TonnageThe gross tonnage G is a standardized measure of a ships capacity. It is calculated in terms of the volume V, in cubic meters, of the ship. There are no units associated with gross tonnage. It is calculated using the formula G=V(0.2+0.02logV). In this exercise, round your answers to the nearest whole number. a.Find the gross tonnage of a ship with a volume of 13,000cubicmeters. b.Use the crossing-graphs method to find the volume of a ship with a gross tonnage of 3000.arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Dispersion Model Animal populations move about and disperse. A number of models for this dispersion have been proposed, and many of them involve the logarithm. For example, in 1965, O.H.Paris released a large number of pill bugs and after 12 hours recorded the number n of individuals that could be found within r meters from the point of release. He reported that the most satisfactory model for this dispersion was n=0.772+0.297logr+6.991r. a.Make a graph of n versus r for the circle around the release point with the radius 15 meters. b.How many pill bugs were to be found within 2 meters from the release point? c.How far from the release point would you expect to find only a single individual?arrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. Logistic Model A population grows according to the logistic model. The r value is 0.02 and the environmental carrying capacity is 2500. Write the logistic equation satisfied by the population if N(0)=100.arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Note Some of the formulas below use the special number e, which was presented in the Prologue. A Population of Deer When a breeding group of animals is introduced into a restricted area such as a wildlife reserve, the population can be expected to grow rapidly at first, but to level out when the population grows to near the maximum that the environment can support. Such growth is known as logistic population growth, and ecologists sometimes use a formula to describe it. The number N of deer present at time 1 measured in years since the herd was introduced on a certain wildlife reserve has been determined by ecologists to be given by the function N=12.360.03+0.55t Figure1 a. How many deer were initially on the reserve? b. Calculate N(10) and explain the meaning of the number you have calculated. c. Express the number of deer present after 15 years using functional notation, and then calculate it. d. How much increase in the deer population do you expect from the 10th to the 15th year?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Growth of Bacteria The organism E. coli is a common bacterium. Under certain conditions, it undergoes cell division approximately each 20minutes. During cell division, each cell divides into two cells. a.Explain why the number of E. coli cells present is an exponential function of time. b.What is the hourly growth factor for E. coli? c.Express the population N of E. coli as an exponential function of time t measured in hours. Use N0 to denote the initial population. d.How long will it take a population of E. coli to triple in size?arrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. Doubling Time If an investment earns an APR of r, as a decimal, compounded annually, then the time D, in years, required for the investment to double in value is given by D=log2log(1+r). a.Find the doubling time for an investment subject to an APR of 5 if interest is compounded annually. b.Plot the graph of the doubling time D versus the interest rate r, as a decimal. Use a horizontal span of 0 to 0.1. c.Does a small change in the interest rate have a greater effect on the doubling time if interest rates are low or if they are high?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Gray Wolves in Idaho The report cited in Example 4.6 tells us that in 2009, there were 870 gray wolves in Idaho, but that the population declined by 19 that year. For purposes of this problem, we assume that this 19 annual rate of decrease continues. a. Find an exponential model that gives the wolf population W as function of the time t in years since 2009. b. It is expected that the wolf population cannot recover if there are fewer than 20 individuals. How long must this rate of decline continue for the wolf population to reach 20?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Using the Laws of LogarithmsFor Exercises 1 through 6, suppose that lnA=3, lnB=4, and lnC=5. Evaluate the given expression. lnABCarrow_forward
- Reminder Round all answers to two decimal places unless otherwise indicated. The Beer-Lambert-Bouguer Law When light strikes the surface of a medium such as water or glass, its intensity decreases with depth. The Beer-Lambert-Bouguer law states that the percentage of decrease is the same for each additional unit of depth. In a certain lake, intensity decreases about 75 for each additional meter of depth. a. Explain why intensity I is an exponential function of depth d in meters. b. Use a formula to express intensity I as an exponential function of d. Use Io to denote the initial intensity. c. Explain in practical terms the meaning of Io. d. At what depth will the intensity of light be one-tenth of the intensity of light striking the surface?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Minimum Monthly PaymentSuppose you have a balance of B dollars on credit card.You choose to stop charging and pay off the card, making only minimum monthly payments.If your card charges an APR of r, as a decimal, and requires a minimum monthly payment of 5 of the balance, then the time T, in months, required to reduce your balance to 100 is given by T=2logBlog(0.95(1+r/12)). Suppose your current balance is 8000. a.How long will it take to reduce your balance to 100 if the APR for your card is 25? Report your answer to the nearest whole month. b.Plot the graph of T versus r. Use a horizontal span of 0 to 0.3. c.Does a larger APR mean a longer or a shorter time to reduce the balance to 100?arrow_forwardReminder Round all answers to two decimal places unless otherwise indicated. Energy Requirements for India In 2009, India consumed 20 exajoules of energy from all sources. one exajoule is 1018joules. It is anticipated that energy requirements for India will increase by 8 per year for the foreseeable future. a.Make an exponential model for India that shows energy requirements E, in exajoules, t years after 2009. b.What are the expected energy requirements for India in 2030?arrow_forward
- Functions and Change: A Modeling Approach to Coll...AlgebraISBN:9781337111348Author:Bruce Crauder, Benny Evans, Alan NoellPublisher:Cengage Learning