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 completely 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

    What is the velocity of a proton with an energy of 0.12 keV?

    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

    What is the velocity of a proton with an energy of 0.12 keV?

    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

    What Are the Applications of Differential Equations in Mathematics?

    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

    What is the velocity of a proton with an energy of 0.12 keV?

    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

    How can I find the 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

    How can I find the 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 a lot for that, didn't realize 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 referring to. Differentiation: Derivative of xa, including for fractional...
  14. J

    Why Does RSA Encryption Return the Original Number?

    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

    Why Does RSA Encryption Return the Original Number?

    Can anyone help with this? Will ask my math/physics teacher tomorrow but wouldn't mind having another go at it first. Cheers James
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