Probability, Christmas presents
I think i need some help with this (pls forgive me for bad English)
Presents under the Christmas tree. 8 for Lisa, 7 for John, 6 for mom, and 5 for dad. It is not possible to see who the different presents belongs to.
I'm pretty sure i got question a) and b) right, but the last part I'm not sure about:
John and Lisa agreed to open one present each. First John opens one, and then Lisa.
c) What is the probability that they both find a present that belongs to them?
d) What is the probability that neither of them find a present that belongs to them?
on c) I thought something like this: P(J|L)= 7/26*8/25 = 56/650 = 28/325
on d) : 19/26*17/25 = 323/325
But I'm not sure I got it right. I think it's more complicated... What bothers me is what if John opens one of Lisas presents? The text does'nt say anything about this, but it says that the last part of the task is rather difficult. Any suggestions?