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  1. J

    Probability that both people are from group X

    Yup even I'm getting ##\frac{5}{17}## which is same as ur answer. Here is how I did: Group X has 10 Indians and total 25 people Group Y has 8 Indians and total 20 people Total there are 18 Indians and 45 people. 2 people selected are Indians. Denominator is ##\frac{18C2}{45C2}## 2 Indians from...
  2. J

    Probability that both people are from group X

    Thanks. I guess there is some typo in original question as I'm not getting any answer that matches options. Thanks for fraction help as well ##\frac{a}{b}##
  3. J

    Probability that both people are from group X

    I think I've done wrong for second case there are 4 greens in X, 7 in Y and 20 balls total. 2 balls are taken and both are green and we have to find P(both are from X) So numerator is 4C2 / 20C2 which is 0.0316 Denominator is 11C2 / 20C2 which is 0.29 Numerator / denominator = 0.109
  4. J

    Probability that both people are from group X

    Okay got it. And for second one. Is my answer correct there?
  5. J

    Probability that both people are from group X

    So then as per your route for second case we have: probability of drawing both green from Urn X is 4C20 And for denominator we have 11C20 Dividing them we get: \frac{4C20}{11C20} = 0.109 Still not getting fraction \frac{a}{b}
  6. J

    Probability that both people are from group X

    We both got right answer. Lol. But why did you combine the urns? I didn't understand how you can do that.
  7. J

    Probability that both people are from group X

    For second question: Urn X has 4 green and 6 red Urn Y has 7 green and 3 red Two balls are taken. Both are green. Probablity that both are from X There are 4 cases. Balls are taken from (X,X ; X,Y ; Y,X ; Y,Y) Probability of each case is 1/4 And we know that both balls are green. So total...
  8. J

    Probability that both people are from group X

    How to type fractions: i'm typing latex code but it's not working \frac a b Anyway for 1st question: Urn X has 4 green and 6 red Urn Y has 7 green and 3 red Pick one ball and it's green, so total number of cases are (ball from Urn X and it's green) + (ball from Y and it's green) which is (1/2...
  9. J

    Probability that both people are from group X

    1/3 is probability that people are selected from group X, since there are only 3 cases. Yeah the sampling confused me as well. I tried with all sampling possibilities but didn't get answer. You're right that this is Baye's problem as the solved examples before this are of Baye's type and they've...
  10. J

    Probability that both people are from group X

    Homework Statement Homework Equations Probability = number of favourable events / all possible events The Attempt at a Solution Group X Y Total people Indians 10 8 18 (total 18 Indians in both group) Total People 25 20 45 (total 45 people in both...
  11. J

    Find the expectation from probability

    Does f(t) have some physical interpretation? Is it like number of cars arriving in one minute or something? Thanks for the continuous help. The earlier method of 3/5 * 1.5 was so much simpler than integration.
  12. J

    Find the expectation from probability

    So if it's infinite options then shouldn't answer be addition of all results. like P (A or B or ....) = P(only A) + P(only B) +....
  13. J

    Find the expectation from probability

    Ok so X is the time when car comes and there is 1 car in five minutes so d(x)/d(t) = 1/5
  14. J

    Find the expectation from probability

    I didn't understand the limits part. When I meant 0 to 1 and 3 to 5 I meant that signal is red from 0 to 1 and then from 3 to 5. In the book why have they taken g(x) as 0 from 0 to 2 and not from 1 to 3. I mean how are they sure that for the time interval of 5 minutes, we have the first 2...
  15. J

    Find the expectation from probability

    Sorry for the late reply. Yeah it's 3/5 * 1.5 = 0.9 Textbook has a few paras on probability density function. I don't know which value to integrate. They've done this: I don't know why f(x) is 1/5 And why is limits 0 to 5 broken as: 0 to 2 and 2 to 5 The limits can also be: 0 to 1 and 3 to 5
  16. J

    Find the expectation from probability

    This is genius. Thanks for this. 2/5 * 1.5 = 0.9. But why did you take 2/5? In 5 minute cycle there would be infinite cases of Red for 3 minutes + green for 2 minutes OR green for 1 minute + red for 3 minutes + green for 1 minute OR Red for 2.5 minutes + green for 2 minutes + red for 0.5 minute...
  17. J

    Find the expectation from probability

    Cars in between? I'll have to take a small intervals. Like 0 to 0.5 and then move on? Yeah the 26/25 bothered me as well. I don't know how book gets 0.9. But even with 1 minute interval, at least my answer should be a good approximate to 0.9. Currently I get 26/25. I don't know where is the...
  18. J

    Find the expectation from probability

    Homework Statement Assume that in a traffic junction, the cycle of the traffic signal lights is 2 minutes of green (vehicle does not stop) and 3 minutes of red (vehicle stops). Consider that the arrival time of vehicles at the junction is uniformly distributed over 5 minute cycle. The expected...
  19. J

    Given f(N) as digital signal, find f(2N -1)

    Yes you are right. The f(2n-1) is actually f(2(n-1/2)). I missed that step as it wasn't in the book. Thanks.
  20. J

    Given f(N) as digital signal, find f(2N -1)

    Homework Statement f(N) is {3, 4, 5, 6, 7} It starts at 5 meaning f(o) is 5. i have to find f{2N-1} 2. Homework Equations [/B] f(N) is given, so first find f(2N) and then delay by 1. The Attempt at a Solution f(N) is {3, 4, 5, 6, 7} finding f(2N) f(0) is 5. f(2 * 0) is 5 f(-1) is 4. f(2 *...
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