What is population: Definition and 277 Discussions

Population is the term typically used to refer to the number of people in a single area. Governments conduct a census to quantify the size of a resident population within a given jurisdiction. The term is also applied to animals, microorganisms, and plants, and has specific uses within such fields as ecology and genetics.

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  1. H

    Differential Equations - Population Dynamics

    1. The problem statement The DE governing a fish pop. P(t) with harvesting proportional to the population is given by: P'(t)=(b-kP)P-hP where b>0 is birthrate, kP is deathrate, where k>0, and h is the harvesting rate. Model assumes that the death rate per individual is proportional to the...
  2. L

    What size of human population can earth sustain?

    A friend of mine said that currently, the "wealthy" 1.5 billion people on Earth consume as much as the poor other 4.5 billion. He also said there are not enough resources (corruption, etc, aside) to have the others live the "rich" life style. Which begs the question... how much human life can...
  3. P

    Human Population: Fact or Fiction?

    i've always been told that the human pop has been going steadily up and up (6E9 in 1999 i think). a site like this http://www.populationaction.org/ seems to support this. now someone has told me this is all a lie by the elite to kill off large segments of the world. ok that's fine - i have no...
  4. C

    What is the Probability of 5 People in a Small Town Getting Cancer in One Year?

    Feeling a bit rusty on my probability - Say you have 70,000,000 people in a country and a small town with 13,700 people. Now, say 3,000 - 5,000 people of the 70,000,000 people become infected with cancer per year. What are the chances 5 people from the small town get infected in one...
  5. S

    How would I go about estimating the population of my daphnia culture?

    The culture is in a standard 10 gallon tank (20"x10"x12"). I started with about 200 daphnia (<1mm to 3mm). I would like to know where I am at right now.
  6. W

    Population half life question

    Homework Statement A parent isotope has \tau_\frac{1}{2}=\delta. Its decays through a series of daughters to a final stable isotope. One of the daughter particles has the greatest half life of \tau_\frac{1}{2}=\alpha-- the others are less then a year. At t=0 the parent nuclei has N_0 nuclei...
  7. T

    Calc 2: Doomsday for Rabbit Population

    Let c be a positive number. A differential equation of the form below where k is a positive constant, is called a doomsday equation because the exponent in the expression ky^(1+c) is larger than the exponent 1 for natural growth. An especially prolific breed of rabbits has the growth term...
  8. E

    Growth of a population of wolves

    Homework Statement A population of wolves grows according to the function N(t)=(10N0)/(1+9e^(-t/4)), where t is in years and N0 is the initial amount. How long from t=0 will the population take to double? Homework Equations Refer to below heading. The Attempt at a Solution Not...
  9. J

    Exponential Population Growth: 1970-1980

    Homework Statement The population of a country is growing exponentially. The population in millions was 120 in 1970 and 150 in 1980. (a) What is the population t years after 1970? (b) How long does it take the population to double? (c) When will the population be 400 million...
  10. R

    Discover the Constant Relative Rate of Population Growth: C=50.25 and k=0.0359

    A population grows at a constant relative rate. After 10 months the population grows to 72, and after 18 months the population grows to 96. Find C and k. the answer I got was c=50.25 and k=.0359 can somebody just double check for me? I don't know if the method I was used was correct.
  11. L

    Trying to predict US population

    Homework Statement I'm given a table of census data for the US. I'm supposed to construct a logistic population model using these numbers: (t in decades and population in millions) P(0) = 3.929, P(6) = 23.192, and P(12) = 91.972Homework Equations dP = P(a - bP) dt P(t) = aP0/(bP0 + (a -...
  12. Z

    The question of the CPT(coherent population trapping)

    In the experiment of CPT( coherent population trapping),we always consider some questions,such as :the temperatue of rubidium vapor cell, the pressure of the buffer gas ,and incidence intensity of laser. if we just want to increase the amplitude of the CPT signal ,what should we do. And I hope...
  13. V

    Population increases with annual rate problem

    Population of Mexico. In 2006 the population of Mexico was 107.4 million. If Mexico’s population continues to grow at an annual rate of 1.43%, then the population in 2028 will be 107.4(1.0143)14 <-------- is an exponent a) Find the predicted population in 2020 to the nearest tenth of a...
  14. M

    Eigenvalues with a leslie population model

    Homework Statement In the Leslie population model, suppose matrix A has a strictly dominant eigenvalue \lambda_1. Age class evolution is given by: x^{(k)} = Ax^{(k-1)}; initial population is x^{(0)}. (i) Initially, let x^{(0)} be the linear combination a_1x_1 + a_2x_2 + ... + a_nx_n, of A's...
  15. M

    Population Modelling Homework: Immigration, Growth & Recovery

    Homework Statement "The very simple population model for a resource limited population with constant immigration, and no breeding, M'(t) = M(S-M) + I attempts to describe the growth of corals on a reef. Function M(t) represents the biomass of corals." a - Explain which term gives the...
  16. T

    Avian flu could wipe out 1/2 of Earth's population?

    I heard that the avian flu could kill more than 3,000,000,000 human beings. Is this really possible?
  17. C

    Solving Population Growth Diff Eq: Is My Approach Faulty?

    I am trying to model the growth of a population which replicates at a rate of 160% every four hours. Also 50 000 members die every hour. so t denoting time in hours, P denoting the population, k being 0.4 I wrote: dP/dt=kp-50 000 *t Is my approach to solving the differential faulty...
  18. O

    95% CI for the population proportion

    Homework Statement A 95% CI for the population proportion of professional tennis players who earn more than $2 millions a year is found to be [0.82, 0.88]. Given this information the sample size that was used was approximately A) 545 B) 382 C) 233 D) 378 Answer: A) 545 Homework...
  19. S

    Age and metallicity of Population I stars?

    I did some research in regards to the age and metallicity of population I stars in hopes to come up with a novel solution to the Fermi Paradox. Anyways, while the metallicity of the oldest Population I stars can be tracked down to be something like -1 (10% of that of the sun) determining the age...
  20. M

    Population Growth over time

    i guess I am trying to find the relationship between population growth and time. bacteria population is 1000 during time 0minutes. bacteria p.: 2000 time: 30 minutes bacteria p.: 4000 time: 60 minutes bacteria p.: 8000 time: 90 minutes bacteria p.:16000 time: 120 minutes...
  21. C

    Mathematical Modeling of Population

    This is a bit of a general question, but does anyone happen to know a good book, resource, or author in the field of accurate population growth and decline modeling? I'd like to find a good academic (non-website) source to get a general idea of the main things a population ecologist looks at...
  22. Loren Booda

    Planets of population II stars?

    Have population II stars been observed or speculated to have planets?
  23. D

    India 450,000"Calculating India's Population: Logic & Facts

    How many people are living in India? With the help of following data can you find How many people were listed as living in India and give logic also ? . The population of some countries is calculated based upon some logic and listed here ( It has no link with the facts) :- . USA...
  24. A

    Integral involving population density

    Homework Statement Hey all I've got a problem to do with population density. It asks for you to show the number of people living between arbitrary points a and b from the centre of the town is equal to: P(a,b)=2\pi\int^{b}_{a}rf(r)dr Where f(r) is the population density. Note that a...
  25. C

    How to find Population mean when there are no data points ?

    Not sure if this is the right place to post homework questions or not, but my math problem is this: A consumer magazine has contacted a simple random sample of 33 owners of a certain model of automobile and asked each owner how many defects had to be corrected within the first 2 months of...
  26. S

    Biology Population Genetics: Inbreeding

    Homework Statement Dolor and her cousin Largo have conceived a child. They are very concerned about the baby, because they have heard that children of close relatives have a higher incidence of birth defects and/or inherited recessive disorders. They know that their maternal grandmother was a...
  27. L

    Logistic growth, population, limits

    The number of bacteria in a lab is model by the function M that satisfies the logistic differential equation dM/dt = 0.6M (1 - (M/200) ), where t is the time in days and M(0) = 50. What is the limit of M(t) as t approach infinity? Do i use the fundamental theorem of calculus?
  28. P

    How can you use U.S. population data from 1790 to solve a differential equation?

    Use P0 = 3.9 (1790 population) as your initial condition to find the particular solution for this differential equation. Note: You may find it easier to solve in terms of the constants a and b. Show all the steps in your solution. This is the last step to a multi-part problem. I basically did...
  29. T

    What is the Carrying Capacity of a Stocked Lake?

    Homework Statement Biologists stocked a lake with `400` fish and estimated the carrying capacity (the maximal population for the fish of that species in that lake) to be `6900`. The number of fish doubled in the first year. Homework Equations The Attempt at a Solution I know...
  30. joema

    Aftermath: Population Zero view of unattended nuke plants

    "Aftermath: Population Zero" view of unattended nuke plants The National Geographic TV special called "Aftermath: Population Zero" explored the consequences if everyone on Earth vanished, particularly from the standpoint of suddenly unattended technical and industrial systems, and especially...
  31. P

    US Population Modeling

    Use P0 = 3.9 (1790 population) as your initial condition to find the particular solution for this differential equation. Note: You may find it easier to solve in terms of the constants a and b. Show all the steps in your solution. This is the last step to a multi-part problem. I basically...
  32. O

    Calculation of Conduction Electron Population for Semi Conductor

    Hi everyone, From this website (link: http://hyperphysics.phy-astr.gsu.edu/HBASE/solids/fermi3.html#c1 ), we get the following expression: Population Density of Conduction Electron = \int ^{\infty}_{Egap}N(E)d(E) = \frac{2^{5/2}(m \pi k T)^{3/2} exp (-E gap/2kT)}{h^3} My questions are based...
  33. P

    News Highest gdp per head of population

    Which country has the potential to have the highest GDP per head of population if its economy was run perfectly? Can one country run a perfect economy if its trading partners do not? Is there a country that can get by on its own with internal markets?
  34. V

    Bacterial death in a growing population

    Hi, I'm writing to you as a graduate applied math student who has taken a recent interest in biology and the modeling of all kinds of microbiological systems, something I plan on continuing with in my PhD. As such, I'm modeling biology without knowing as much about it as I should :P My...
  35. R

    (Bio} Calculating Aphid Population

    Homework Statement In summer months, female aphids reproduce by parthenogenesis, giving birth to females from unfertilized eggs. These females mature within 24h and begin reproducing in the same way. Assume that each female aphid produced two females the day after she herself is born, and and...
  36. L

    10.7 Small-Sample Inferences Concerning A Population Mean

    Homework Statement Dissolved O2 Content. Industrial wastes and sewage dumped into our rivers and streams absorb oxygen and thereby reduce the amount of dissolved oxygen available for fish and other forms of aquatic life. One state agency requires a minimum of 5 parts per million (ppm) of...
  37. N

    Malthus' Principle of Population Growth: Solving a Differential Equation

    Malthus' principle of population growth can be written as the differential equation y'=ky where y(t) is the population t years after the initial measurement and k is the growth constant. The solution to this differential equation is given by y(t)=Ae^{kt} where A is the initial...
  38. F

    Can Anyone Help with Calculating Population Growth?

    Can anyone tell me how to calculate population growth. my book doesn't tell me how to do that. is the formula rN=dN/dt
  39. R

    Exploring Neutron Population in Sub-Critical Reactor with Heavy Water Reflector

    Consider a reactor being held sub-critical, Keff < 1, by control rods. The reactor has heavy water reflector and has been operatored for some time prior to the current state (we got Photo Neutrons). Keff is then bought to 1. It seems to me, for Keff = 1 the neutron population should be...
  40. K

    Population Allele Frequency and Heterozygotes in H-W Equilibrium

    A population has two alleles, B and b. the allele frequency of B is 0.73. what is the heterozygotes frequency, if the population is in H-W equilibrium?
  41. I

    Rotational spectra - thermal population of rotational levels

    Homework Statement If the thermal population of the rotational levels is given by: Nj/No = (2J+1)*exp(-hcBJ(J+1)/kT) Calculate which state has the highest thermal population at a given temperature T. Calculation needs to be shown, not just a result. Homework Equations Nj/No =...
  42. A

    Population Growth Modelling

    The Problem: Consider a species in which no individuals live beyond 3 years. Divide the population into four age groups labelled by n = 0,1,2 and 3. Assume that only the second and third groups can reproduce. For each group n let bn denote the birthrate and d_n the death rate. Find a matrix A...
  43. O

    Is population reduction the solution to environmental problems?

    Here is the full question: Reducing human population, disregarding the difficulty, would be the most effective way to: - reduce pollution (air, water, soil, noise...) and - avoid depleting natural resources (fish stocks, oil, forests...) and - prevent extinction of living species, as well as -...
  44. Mk

    50% reduction in penguin population

    I watched 60 minutes today and they used a new example of global warming in action! The journalist was talking to two arctic biologists, and the man said that there has been a 50% reduction in penguin population. That sure sounds like a big number! Is that true? I don't believe a mention of the...
  45. J

    Population Question Using Half-Life Equation

    Homework Statement Vancouver Island has an area of 33000km^2 but no wombats. If we release a pair of wombats on Vancouver Island and their annual rate of increase is 50%, how many years will it be before the wombat population reaches one pair per km^2? Homework Equations [A]t=[A]oe^-kt...
  46. K

    A Model of Human Population Growth: Is a Breaking Point Coming?

    i was just wondering abt this thing for a while... the total no. of human beings are increasing over the decades...which means some %ge of the Earth's matter is getting converted in the form of humans...suppose if the population goes on increasing, then theoretically there should be only humans...
  47. D

    Calculating Population Mean in Excel

    Hello, i am having trouble with working out what the population mean is. Is there a formula in Microsoft Excel to workout the population mean. I have a population of 200
  48. R

    Stellar Population in Milky Way

    Hey folks, I'm currently at grad school and am working on an algorithm to try and model the rate of supernova (type I and II) in our galaxy. I really need to know the following information. 1) Where can I find information on HOW MANY of the different types of stars there are in our...
  49. B

    Differential equations - population growth models

    The initial mass of a species of fish in a lake is 7 million tonnes. The mass of fish, if left alone, would increase at a rate proportional to the mass, with a proportionality constant of 2/year. However, commercial fishing removes fish mass at a constant rate of 15 million tonnes per year...
  50. T

    Population model: dP/dt = k sqrtP

    Homework Statement Suppose that when a certain lake is stocked with a population P of fish, the birth and death rates \alpha and \beta are inversely proportional to \sqrt{P} , so that \frac{dP}{dt} = k \sqrt{p} Find P(t) if P(0)=C The Attempt at a Solution \frac{dP}{\sqrt{p}} = k dt...
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