Recent content by James...

  1. J

    Normal distribution - Finding mean and standard deviation

    Many thanks for the reply, and you are correct. I was using the table wrong and now understand how it all works properly. Thanks for taking the time to reply. JAmes
  2. J

    Normal distribution - Finding mean and standard deviation

    Thanks for the reply, but I get that part. I was wondering about the values of 0.8779 and -0.5534 I think they are correct for the corresponding probabilities but the answer got different values. So it's actually the Z1 and Z2 values I need checking. After that, I'm fine. CHeers James
  3. J

    Normal distribution - Finding mean and standard deviation

    Homework Statement A high jumper knows from experience that she can clear a height of at least 1.78m once in 5 attempts. She also knows that she can clear a height of at least 1.65m on 7 out of 10 attempts. Find to 3 dp the mean and standard deviation of the heights the jumper can reach...
  4. J

    Geometric Distribution Question

    Cheers! I know the actualy calculation is done right. Just wasn't completly sure if I'd used the right method. I stupidly left the notes I did for the question at University and I'm revising now at home so can't check over them.
  5. J

    Geometric Distribution Question

    Homework Statement An experiment consistion of tossing three fair coins is performed repeatedly and "success" is when all three show a head. What is the probability that the success is on the third performance of the experiment? Homework Equations Geometric distribution equation p(x) =...
  6. J

    Velocity of a proton question

    So would the correct answer be... 120 * 1.6 x 10-19 = 1.92 x 10 -17 sqrt(2*1.92 x 10 -17/1.7 x 10-27) = v = 1.5 x 105 ms-1
  7. J

    Velocity of a proton question

    By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electrostatic potential difference of one volt. (from Wiki) Oh, my tutor told me to divide... Is it because 1 Volt = 1 Joule/1 Coulomb There for Joules = V * C...
  8. J

    Differential Equation Uses

    We did the basics of solving differential equations in Maths this week, well, it was actually just finding other approximate values of y for an equation given the derivative and a pair of co-ordinates on it. Are these for equations that cannot be subject to intergration? Also, what can...
  9. J

    Velocity of a proton question

    Homework Statement Calculate the veolcity of a proton of energy 0.12 keV proton mass = 1.7 x 10^-27 Homework Equations The Attempt at a Solution I thought... 0.12 keV = 120 eV 120/1.60 x 10^-19 = 7.5 x 10^20 J E = 0.5mv^2 sqrt(2E/m) = v but I'm getting something to x 10^23 so its...
  10. J

    Roots of a cubic equation

    Many many thanks for your replies, I think I will try and have a go at studying the things you mentioned in your first post for definate! Anything that will expand my knowledge and help me at University can only be a good thing! I managed to get the answer by creating a linear and quadratic...
  11. J

    Roots of a cubic equation

    I've been looking at some practise exams for the University I would like to apply to, I have to sit the exam on 4th November. We have never done finding the roots of a cubic equation before and I cannot figure it out from looking on the internet, the formulas are all horrible to understand...
  12. J

    Derivative of a sum of functions, also cubic graph roots

    Thanks alot for that, didn't realise that was it, glad they are something easy & not hard. I will do a bit of digging on the cubic then and try to work it out ;)
  13. J

    Derivative of a sum of functions, also cubic graph roots

    Derivative of a sum of functions What would you interperate this as? It is one of the subsections of Differentiation from the syllabus of a University entrance Exam in November but I cannot think what it is refering to. Differentiation: Derivative of xa, including for fractional...
  14. J

    RSA Algorithm Help

    I think you are right but I am getting fractions when the modulus function is introduced as I'm unsure how it works. James
  15. J

    RSA Algorithm Help

    Can anyone help with this? Will ask my math/physics teacher tomorrow but wouldnt mind having another go at it first. Cheers James
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