# Search results

1. ### Help with Combinations

Thank you very much.
2. ### 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. ### 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. ### If P, then Q

Thank you very much
5. ### 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. ### 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. ### A number

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