How to solve this math question, data management, probability using counting?
1. So on this one, it’s like there are only 8 possible choices for the girl to pick, since she always replaces her own. So then there is only 1 way she can pick the two other sisters. Overall, there are (8 choose 2) = 28 possible other pairs of people she can pick (since there are 8 options for the first, 7 for the 2nd, and then divided by 2 since the order in which they are picked doesn’t matter), so the probability is 1 / 28. 2. So now order matters on this one, when it didn’t matter which sister you picked first on the last one. Again, there is only 1 way to pick the middle sister first and then the eldest one second. Overall there are 8 x 7 = 56 possible outcomes (since there are 8 options for the first, 7 for the 2nd, and the order does matter), so 1 / 56 is the probability.
