Timeline for Intuition behind permutations + probability
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 22, 2021 at 11:22 | vote | accept | lkdlst | ||
| Apr 22, 2021 at 10:57 | comment | added | Henry | You might want to read about rencontres numbers | |
| Apr 22, 2021 at 10:28 | comment | added | lkdlst | Right so $\frac{10!}{7!}$ should be $\frac{10!}{3!}$ and for the last one if it was matched incorrectly then that means it isn't possible to have the other 9 be correct - what if the question was instead asking about matching exactly 8 out of 10 correctly? | |
| Apr 22, 2021 at 10:24 | comment | added | Henry | $\frac{1}{10!}$ is correct. $\frac{10!}{7!}$ is not: if the first seven are correct, then you are counting the number of permutations of the last three. The final question has two possible answers: either the other word was matched correctly or it was matched incorrectly, and each of those has logical implications | |
| Apr 22, 2021 at 10:16 | comment | added | lkdlst | Thanks! Here's what I've got so far. • $10!$ permutations possible • $\frac{1}{10!}$ permutations gets all 10 correct • $\frac{10!}{7!}$ get the first 7 correct? • Not too sure for the last one | |
| Apr 22, 2021 at 10:11 | history | answered | Henry | CC BY-SA 4.0 |