normal

  1. O

    Normal form of a line example

    My textbook didn't explain normal form of a line that well, so I'm a quite confused about the example they gave to illustrate the concept further. As follows: First, how do you get from $\vec{n}\vec{x} - \vec{n}\vec{p}$ to $x + y + z - 2$? Second, it says "using the row reduction algorithm"...
  2. O

    Normal form definition

    I have two questions about the normal form of a line that I hope someone can help clarify: 1. When considering the normal form of a line, does this line need to be a line that doesn't cross through the origin? Based on this definition below, it appears that it can't cross the origin, but...
  3. K

    Normal distribution with unknown mean and sigma

    The weight of a Dog is normally distributed with mean A kg and standard deviation B. Find: a) The probability that a Dog is less than 35 kg b) The probability that a dog is greater than 32 kg I have not dealt with unknown Standard deviation nor mean before. I have a TI graphical...
  4. R

    a question about 'properties of multivariate normal distributions'

    hello guys, i have a question and looking for an answer quickly... :) question; prove that, Z is a vector. thank you.
  5. N

    statistical tables

    In this question for calculating the confidence interval why do they use the sample mean of 0.9986 instead of just one pint?
  6. X

    Unit tangent vector vs principal normal vector difference

    http://mathwiki.ucdavis.edu/Core/Ca.../The_Unit_Tangent_and_the_Unit_Normal_Vectors In the link, I cant understand that why the Principal Unit Normal Vector is defined by N(t) = T'(t) / | T'(t) | ,can someone explain.... Since tangent vector is normal to principal normal vector, why the N(t)...
  7. X

    normal vector in surface integral of vector field

    when the normal vector n is oriented upward , why the dz/dx and dz/dy is negative ? shouldnt the k = positive , while the dz/dx and dz/dy is also positive?
  8. L

    Adding probabilities of normal distributions

    I have 2 questions on the topic of adding together probabilities. see bold text: Example: So if you have 3 stochastic variables with their own normal distribution A; B; C. Let's say they represent the percipitation per month in 3 different locations. A = N(25;4) B = N(26;7) C = N(23;3)...
  9. L

    Probability from a skewed "normal" distribution

    So i have a datasample and when i plot a histogram it is a skewed distribution. (i think i managed to attach a picture?) So i know how I would fit a normal distribution to it and calculate for instance the probability of x being -4 or smaller but this isn't accurate to model it in that way. so...
  10. I

    Uniform quantizer with normal distribution input

    A signal that has amplitudes with zero mean and unit variance is applied to a quantizer that is a 8 level uniform quantizer with levels -3.5*d, -2.5*d .... 3.5*d, pick d so that the probability X falls outside th range of the quantizer is 1%My approach to this problem was to use a q function...
  11. A

    Normal distribution question

    Dear everyone Greetings, I have a question i need help with: John wants to investigate the actual weight of carbonated soft drinks sold in the mart contained in 1.5-litre bottles purchased from a nationally knownmanufacturer. A random sample of 40 bottles is selected, and the samplemean and...
  12. P

    Random Samples with normal distribution given mean and variance

    Hello! So I know this problem should be super easy but for some reason I can't figure out how to do it. Any formulas/direction/etc is appreciated Suppose X1.....Xn are random samples from normal distribution with mean u and variance r2 When n=10, calculate P(x bar is within u plus or minus...
  13. A

    Airline Normal probability

    I just want to know that my train of thought is correct because sometimes I get the right answer with the wrong way of thinking. Since the percentage of no shows at flight time is 2%, then the percent of the people who do show up is 98%, which is our p. Sample space is 200 since we want to...
  14. A

    Quick question about a normal probability distribution problem

    In part b, it asks to find the x value and we're given a percentage (5%). If you look at a normal table, 5% corresponds with a z-score of -1.645. Why is it that we need to convert the negative z-score of -1.645 to a positive when we plug it in the formula to solve for x? Using the negative...
  15. A

    Finding probability using normal distribution

    I've searched this question on other forums. There are people who are saying that n = 197 and some are putting n = 200. I feel like 200 is the right n because we want to choose 197 from 200 to show up. Am I right?
  16. K

    Help with this stats problem - normal distribution

    I have figured out parts a-c, but I wouldn't be opposed to someone checking my work. I unfortunately don't even know how to start d. I'm not looking for the outright answer, but I hint in the right direction would be greatly appreciated!! I have no clue how to start it :/ Metal balls for ball...
  17. S

    Find variance of normal distribution, given mean and...

    Hello! I am trying to solve this question, which is supposed to be relatively easy, but it's taking me more than an hour and I still cannot. The problem is: I would really appreciate help! I am trying to solve it using Chebyshev's theorem, but perhaps this is wrong? Thank you!
  18. E

    Normal and composition series (groups).

    Let G and H be finite groups. I there are normal series of G and H having the same set of factor groups then G and H have the same composition factors. Alright. Therefor, S and T, said normal series, have the same length (and so |G| = |H|). I give an example. S= G > G_1 > 1 and T= H > H_1 > 1...
  19. J

    When to use the t or normal distribution?

    We got our midterm back, and i'm confused on what the answer was to this question. Suppose you are given a random sample of 41 observations on student heights in inches and youcalculate a mean of 65” with a standard deviation of 3.75”. You are asked to construct a 95%confidence interval based...
  20. A

    Normal distribution for X=3

    Hello everyone Greetings. I have a question below: A school student found that the time spent on homework were normally distributed, mean 55 minutes and variance 81 minutes. Find the probability that 3 assignments each take more than 60 minutes. Solution from textbook:0.0242 My working: X=...