Permutation and combination

  1. For this question, i already solve the part a and part b. For the part c, i try to solve it but i cant get the answer that given. Can someone explain to me? How to do the part c. Thanks!
     

    Attached Files:

  2. jcsd
  3. tiny-tim

    tiny-tim 26,054
    Science Advisor
    Homework Helper

    Hi kschong! :wink:

    So there's 24 tanks, of which 6 are high viscosity, add 4 are high impurity: what is the probability that 4 tanks chosen at random include exactly one of each?

    Show us your full calculations, and then we can see what went wrong, and we'll know how to help. :smile:
     
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