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  1. O

    Help with Combinations

    Thank you very much.
  2. O

    Help with Combinations

    I'm a bit confused. I simply multiplied in the first case: (3 ways to choose the first 2 letters that are the same) * (3 ways to choose the third letter) = 9 And did the same in the second case: (4 ways to choose the first letter) * (3 ways.... the second) * (2 ways... the third)= 24 I did...
  3. O

    Help with Combinations

    How many combinations of three letters from the letters A,A,B,B,C,C,D are ther? ------------------------------ I assumed 2 cases: 1. 2 letters are the same. 2. all the 3 are different. And found 9 forms for the first case, and 24 for the second one. As you know my answer (33) is 20 more...
  4. O

    If P, then Q

    Thank you very much
  5. O

    If P, then Q

    Your examples clear things up. Can you give me some more examples for the truth values of P->Q ? I know when we have P , Q there are 4 possible truth value for p-> Q : P Q P->Q 1. T T T 2. T F F 3. F T T 4. F F T Fore...
  6. O

    If P, then Q

    In the statement P -> Q , Q is necessary for P. I just don't get it ,why don't we say P is necessary for Q, can you illustrate it in an example ? :redface:
  7. O

    A number

    I just wanted stat to help me with this decision. :biggrin:
  8. O

    A number

    No ,no ,..... I meant, can stat provide me with a number that indicates which one of the books I must read at the moment to finish all the books at a (nearly) certain time ? In other word ,... Forget it. Stat had better stay at the books and the exams, not in the real life situations.
  9. O

    A number

    A number !! I am going to read 10 books in a certain period of time. The number of pages of the books varies between 40 and 1000 pages. I need to finish them in almost the same time, so I must read each book with a certain rate. What I need is a number to indicate the priority of each book...
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