It's actually a binomial distribution. If you want a process and need to talk about binomial distribution once, then I will talk about it once:

Red fish, China fish, half,

Therefore, according to the principle of multiplication,

The probability (for example, "middle red" and "middle red ...") that all the five released fish are specified species is (1/2) 5 = 1/32.

Therefore, the probability of two China fish in five fish is equal to 1/32, multiplied by the combination number of two out of five (the position of two China fish in five fish is different, * * * c (5,2) 2)= 10/0 possibility).

The answer is 10/32=5/ 16.

There is only one fish in China: C(5, 1)/32=5/32.