Current location - Training Enrollment Network - Mathematics courses - A mathematical probability problem 20 1 1 Chongqing college entrance examination problem
A mathematical probability problem 20 1 1 Chongqing college entrance examination problem
X= 1 means that everyone chooses the same area as 1.

P(X= 1)=3/3^4= 1/27

X=2 indicates that two regions have been applied.

p(x=2)=a(3,2)*c(4, 1)/3^4=8/27

(Choose two of the three zones, take photos in sequence, then four people choose 1 zone, and the remaining three choose the second zone. )

Please accept if you are satisfied, and ask again if you don't understand.