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  1. Sirsh

    Complex Number Division and Addition

    I have never heard of the distributive law before, but have applied it naturally when doing maths I think. I can re-arrange the equation and get this I think: Zp*Xm + Zp*Zr = Xm*Zr Zp*Xm = Xm*Zr - Zp*Zr Zp*Xm = Zr(Xm-Zp) (Zp*Xm)/(Xm-Zp)=Zr Is this correct? I can then substitute my values...
  2. Sirsh

    Complex Number Division and Addition

    Homework Statement This is not for a mathematics unit but is part of an electrical question I'm trying to solve but I cannot solve this equation. The complex numbers Zp and Zr are both real and imaginary, whereas Xm is purely imaginary. Homework Equations Zp = (Xm*Zr)/(Xm+Zr) Zp =...
  3. Sirsh

    Degrees of confidence

    Thanks alot, gerben!
  4. Sirsh

    Degrees of confidence

    Hi, I'ld like to know if anyone knows how to find the 'z' score inrelation to a percentage degree of confidence. The question is: Determine the z score that would give a result with a degree of confidence of 95%. I know that it is, 1.9600. However, I would like to know how to figure this out...
  5. Sirsh

    Geometric proof.

    Hello all, the picture i have attached is the question. http://img842.imageshack.us/img842/8921/geometricproof.png [Broken] I've concluded that there are two i isosceles triangles in this one triangle. \anglePSQ + \angleQSR = 90degrees Finding the angle in one of the isosceles...
  6. Sirsh

    Rate of change question (pretty confusing)

    3. The volume of a tank used to provide water for animals at an animal enclosure at the local show is given by V(h) = (0.2h^3+3h)m^3 where h metres is the depth of the water in the tank at any time t seconds. Water is being added to the tank at a constant rate of 0.4 m3 per second. Find the...
  7. Sirsh

    HARD equation.

    I am confused, I know that you can solve for three variables by doing an eliminiation process like a silmutaneous solving method, but i dont understand how to get it to the three equations..
  8. Sirsh

    HARD equation.

    How is that possible, i'd have to solve for 4 unknowns A,B,C and x? (Ax^2+Ax+x^2B+x^2C-xB-C)/(x^3-x) is the LHS
  9. Sirsh

    HARD equation.

    Hi, i'm just wondering if anyone can help me with this equation: I need to determine the values of A,B and C from the given equation. \frac{A}{(x-1)} + \frac{B}{(x+1)} + \frac{C}{x} = \frac{5x^2+2x+1}{x^3-x} I've tried to simplify it by factorising the denominator on the LHS to x^3 - x...
  10. Sirsh

    Applications of Calculus

    Um, Does the equation mean that: the derivative of P divided by P equals 0.2 times the derivative of t?
  11. Sirsh

    Applications of Calculus

    dP/0.2P = dt? or dP/P = 0.2dt
  12. Sirsh

    Applications of Calculus

    Hi all, I'm just wondering if this is correct: \frac{dP}{dt} =0.2P If the population is now 5300: (a) Write a formula for the population in t years time. To do this would i antidifferntiate 0.2P, so.. (0.2P^2)/2 = 0.1P^2 + t? Thank you!
  13. Sirsh

    Normal distribution

    So would the probability of a certain flare be 0.9 then you'd have to find the z score, then put the z scores value into the equation z = (x-mean)/stnd dev and then you'd find the x value and that'd be the amount of years it would work for?
  14. Sirsh

    Normal distribution

    3. A local manufacturer creates distress flares. The times the flares last are normally distributed with a mean life of 9.8 years and a standard deviation of 1.3 years. (b) A small boat owner who regularly travels out to sea wants to be sure his distress flare works. Determine when he should...
  15. Sirsh

    Determine the probability that a random variable

    Pretty much finished the assignment before you replied lmao.
  16. Sirsh

    Very hard distribution question!

    The school psychologist was researching the results of a third school and found them to closely fit a normal distribution with a mean completion time of 20.68 minutes and a standard deviation of 5.3 minutes. Unfortuantly, after he had finished calculating the results, he could not read of of the...
  17. Sirsh

    Determine the probability that a random variable

    Hello my question is stated below: Task 3: Determine the probability that a random variable (X) having a normal distribution with μ = 20.15 and σ = 6.27 minutes will take on a value less than 9.5. I've tried this: Standardised score = (9.6-20.15)/6.27 = -1.698 Now i dont know how...
  18. Sirsh

    How do i read a frequency graph?

    Thank you. Do you know how i'd go around getting the stadard deviation? Is it root(x-mean)^2/n?
  19. Sirsh

    How do i read a frequency graph?

    Sorry i meant. |Time required to complete test| Frequency | Midpoint | | 5-9 | 6 | 7 | | 10−14 | 12 | 12 | | 15−19 | 25 | 17 |...
  20. Sirsh

    How do i read a frequency graph?

    How do i read a frequency graph?? If i have. a time required of 5-9 and a a frequency of 5. how do i find the average? do i do 9-4*6 or 9*5+5*9/5 ?? thanks.
  21. Sirsh

    Gaussian distribution problem

    Willem2, You see that 'Q' at the start of the thread, that means Question! He means that at the centre of a normal distribution bell curve, there are three pieces of information that are avaliable to be found out by using just the middle of this curve. i.e. 'Something,Something and Something'...
  22. Sirsh

    Definite Integrals

    Thanks alot HallsofIvy, I don't really understand. could you please do an example of both?
  23. Sirsh

    Definite Integrals

    Wow, i'm so retarded I forgot to actually intergrate the function. how embarrassing..
  24. Sirsh

    Definite Integrals

    With both did you do F(b) - F(a) ? also, do you know anything about these type of intergrals. \intf(x)dx+|\intf(x)dx| |\intf(x)dx|+\intf(x)dx |\intf(x)dx+\intf(x)dx| I'm unsure what these | | parts do when theyre associated with the integral. thanks alot.
  25. Sirsh

    Definite Integrals

    I only did the one area for the 2nd function, ignore the 1st function.
  26. Sirsh

    Definite Integrals

    Hi all, just wondering if someone could explain to me about define integrals. Say i have F(x)=0.5x2-2 and F(x)=x3+x2-6x and i want to find the area of the regions which is satisfied from -2 to 2. so \int0.5x2-2 from -2 to 2. \intx3+x2-6x from -2 to 2. Now with the cubic, from -2 to 0 is...
  27. Sirsh

    Graph analysis - how closely histogram fits poisson curve

    Finding area under a curve is apart of calculus. http://en.wikipedia.org/wiki/Integral
  28. Sirsh

    Factorising - 2 brackets

    Yes, i've got to agree with you. completely forgot about roots of the functions. (:
  29. Sirsh

    Probability question

    1) what is the probability that the first number picked is one of them? 6C1 out of 45C6? with the other one's im unsure, my school has supplied me with virtually no materials to learn probability with neither which i can find on the internet, sorry.
  30. Sirsh

    Probability question

    Six numbers are randomly selected from 45 numbers. Once a number is selected it is not replaced. Determine the probability of correctly predicting: a) exactly four of the six numbers b) at least four of the six numbers. a) 4C4/45C6 b) 4C4+4C3+4C2+4C1+4C0 / 45C6 i'm completely...
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