- #1
Addez123
- 199
- 21
- TL;DR Summary
- On a lottery ticket you can choose 1,x,2 as answer on 13 questions.
Whats the odds that you get exactly 12 correct answers?
The odds are:
$$\frac {1}{3}^{12} * \frac {2}{3} * 13P1$$
And it's the 13P1 that I don't understand.
It's basically saying, among 13 lines, how many ways can 1 line be choosen to be incorrect?
Shouldn't 13P12 be equally correct?
That would be like saying: Among 13 lines, how many ways can 12 lines be choosen correctly?
My question is, why 13P1 and not 13P12?
Maybe it should be 13C1?
But that doesn't make sense since combinations doesn't regard order. Having first answer wrong isn't the same as having second answer wrong. So I should be using permutations, right?
$$\frac {1}{3}^{12} * \frac {2}{3} * 13P1$$
And it's the 13P1 that I don't understand.
It's basically saying, among 13 lines, how many ways can 1 line be choosen to be incorrect?
Shouldn't 13P12 be equally correct?
That would be like saying: Among 13 lines, how many ways can 12 lines be choosen correctly?
My question is, why 13P1 and not 13P12?
Maybe it should be 13C1?
But that doesn't make sense since combinations doesn't regard order. Having first answer wrong isn't the same as having second answer wrong. So I should be using permutations, right?