i******e
发帖数: 1811 | 1 The jones family household includes Mr. Mr. Jones, four children, two cats,
and three dogs. Every six hours,there 's a Jones family stroo. The rules for
a Jones family strool are:
Exactly five things (people+dogs+cats) go on each stroll
Each stroll must include at least one parent and at least one pet
There can never be a dog and a cat on the same stroll unless both parents go.
All acceptable stroll groupings are equally likely.
Given that exactly one paretn wen to the 6pm stroll, what's the probaility
that Rover, the oldest dog, also went?
求思路和解答，叩谢 |
|
