1. I

    Defining a formula to determine the relationship and positioning 3 moving averages

    Hi, I have 3 moving averages. 2 define a channel (high/low) and the 3rd constantly moves within the high/low channel. I'm trying to create a formula that represents the relationship between the 3 moving averages but I don't know how to achieve this. Could someone suggest how I go about this...
  2. Z

    Modelling with Recurrence Relation

    This is a question from my tutorial. A patient is injected with 80 ml of an antibiotic drug. Every 4 hours 40% of the drug passes out of her bloodstream. To compensate for this an extra 15ml of antibiotic is given every 4 hours. Find a recurrence relation for the amount of drug in the...
  3. C

    Modelling Reflexivity with a Time Series Model

    Hi there, I'm new to this forum so hi to everyone! I would like to find a time series model that is capable of modelling two time series with following properties: 1) consider time series X and Y. X is influencin Y positively and vice versa so that they move in the same direction. However one...
  4. P

    Population Modelling

    Hi all, I'm looking for some help with questions (1) and (2) here. Would be greatly appreciated! Imgur Thanks
  5. D

    Differential Equations / Integration - Please help!

    Hello. I've been doing my differential equations coursework recently and I am so close to finishing it but I have one last bit I'm stuck on. The coursework aim is to model 2 equations, representing the velocity of an aeroplane that has just landed (at t=0). All we are given is a table of...
  6. P

    Modelling the motion of a meteor

    Hi! I am to model the motion of a meteor as it travels through the atmosphere, taking into account the loss of mass, which is 0.025 kg upon impact (height = 0). I also have to take into account the air resistance on the meteor, the fact that the air density is a function of height and that the...
  7. G

    ODE - Species population modelling

    Hi guys, I would like some help on this problem. I have a quiz soon, which is on this problem set. I can't get help tomorrow as I have classes all day. I have been really busy during the last few weeks on the family farm. I have hired a personal tutor, but we don't start until after...
  8. maxpancho

    Exponential modelling, word problem

    Shouldn't the equation here be $I(d)=I_o(1-\dfrac{0.15}{3})^d$? It's different at the end of the book and I don't see why.
  9. G

    Mathematical Modelling ( steady states)

    non-dimensionalisation equation: \begin{equation} \frac {du}{d\tau}=\frac{\overline{\lambda}_{1} u}{u+1} -\overline{r}_{ab}uv -\overline{d}u \end{equation} where $\overline{\lambda}_{1}= \frac {\lambda_{1}}{\lambda_{2} K_{1}}$ Another non-dimensionalisation equations \begin{equation} \frac...
  10. G

    Mathematical Biology (Modelling)

    Consider the two species competition model given by da/dt = [λ1 a /(a+K1)] - r_(ab) ab - da, (1) db/dt = [λ2 b *(1-b/K2)] - r_(ba) ab , t>0, (2) for two interacting species denoted a=a(t) and b=b(t)...
  11. T

    Modelling a pong game

    OK, imagine a game called pong, which is played between two players as a sequence of points. The first player to win three points wins the match, so a match can have three, four or five points in total. Suppose the same two players, A and B, play ten pong matches. We intend to model pong on the...
  12. A

    Modelling dependence between two random variables

    There are a few ways to model/represent the dependence between two random variables. For example there is the linear correlation or one can write one random variable as a function of the other. Then there is also copula functions that can be used to model dependence between two variables. I was...
  13. M

    modelling using mathematics

    Hi all, just stuck on this maths does anyone have any advice or know how to go about answering it. 4 Balloons were released from ground level at the same time, each with different volumes of helium within. Ignoring wind resistance, the maxium height were measured in meters (m) as follows...
  14. A

    Normal Distribution (modelling)

    Hi, Need help with a question on normal distribution. Question The time required to complete a certain car journey has been found from experience to have mean 2 hours 20 minutes and standard deviation 15 minutes. It is known that delays occur rarely on this journey, but that when...
  15. J

    modelling population growth/decay

    I have another question I would like to ask about, this is the question as follows ******************************************************************* The simplest useful model for a shery comes from the logistic model for population growth, together with a harvest h which is proportional to...
  16. N

    Quadratic and logarithmic modelling

    Hey guys, ok i'll start off with my answer! PS: I have no idea how to make my written answers show appropriately. For the quadratic model, I get: f(x)=1/80x2+15 and for the logarithmic model: f(x)=30(1+ Ln(x/25)/Ln(12/5)) ------------Re-checking ---------------------...
  17. M

    modelling for designing a pedestrian crossing

    This question has been asked before but no clear guideline on how to tackle it were provided, please help me.A two lane road has been made one-way to create additional parking. Parking is allowed on the LHS, whilst traffic is free to move on the RHS. Most of the parking space is occupied during...
  18. L


    A radio active element is know to decay at the rate of 2% every 20yrs. If initially you add 165g of the element, how much would you have in 60yrs. what is the half life time of the element. i formulated the model as E_{t+1} = 1.02E_{t} , where t \sim O(20) E_{0} = 165g t= 0 solution...
  19. L

    mathematical modelling!

    A conical tank of height 3m is full of water and the radius of surface is 1m. After 8 hrs the depth of water is 1.5m. If we assume that the water evaporate at a rate proportional to the surface area expose to the air, obtain a mathematical model for predicting the volume of water in the tank at...
  20. E

    Trigonometry - modelling and problem solving

    Can you tell me if I have the correct answer for the following problem. Standing due south of a tower 50m high, the angle of elevation to the top is 26 degrees. What is the angle of elevation after walking a distance of 120m due east? I have an answer of 17.6 degrees