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Mathematics Dictionary
Dr. K. G. Shih

Probability : Hypergeometric

Formula
h(x) = C(k, x)*C(N-k, n-x)/C(N,n)


  • Q01 | - Hypergeometric formula
  • Q02 | - Example : A hand of bridge cards have 0 spade
  • Q03 | - Example : Take five cards and expect 4 aces
  • Q04 | - Example : 24 electric bulbs with 12.5% defective

  • Q01. Hypergeometric formula

    Formula
    • h(x) = C(k, x)*C(N-k, n-x)/C(N, n)
    • N = Total sample
    • n = Take number of samples
    • k = Take total samples
    • x = Expect happen events

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    Q2. Thae five cards with 4 kings

    • N = 52 cards
    • n = Take 5 cards with expected 5th card
    • k = 5 cards are taken
    • x = 4 kings
    • h(x) = C(5, 4)*C(52 - 5, 5 - 4)/C(52, 5)
    • h(x) = 5*C(47, 1)/C(52, 5)
    • h(x) = (5*47)/((52*51*50*49*48)/(5!))
    • h(x) = (5*47)*(5!)/(52*51*50*49*48)
    • h(x) = (234*120)/(52*51*50*49*48)
    • N = 52 cards
    • n = Take 5 cards with any 5th card
    • k = 4 cards are taken
    • x = 4 kings
    • h(x) = C(4, 4)*C(52 - 4, 5 - 4)/C(52, 5)
    • h(x) = 1*C(48, 1)/C(52, 4)
    • h(x) = 48/((52*51*50*49)/(4!))
    • h(x) = 48*(4!))/(52*51*50*49)
    • h(x) = (48*24)/(52*51*50*49)
    • h(x) =

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    Q4. 24 electric bulbs with 12.5% defective

    • N = 24 bulbs
    • n = Take 3 bulbs
    • k = Defective bulbs = 24*0.125 = 3
    • x = Expected defective in the 3 bulbs = 0, 1, 2 or 3
    • Take 3 bulbs without defective one
      • h(0) = C(3, 0)*C(24 - 3, 3 - 0)/C(24, 3)
      • h(0) = 1*C(21, 3)/(24, 3)
      • h(0) = (21*20*19)/(24*23*22)
      • h(0) =

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    AL 17 00. Outline


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