在一袋中有10 个相同的球，分别标有号码1,2,…,10。每次任取一个球，记录其号码后放回袋中，再任取下一个。这种取法叫做“有放回抽取”。今有放回抽取3个球，求这3个球的号码均为偶数的概率。(There are 10 same balls in a bag, marked 1,2, respectively. 10. Each time you take a ball, record its number and put it back in the bag, then take the next one. This method is called "put back extraction". 3 balls are extracted and extracted, and the probability of the number of the 3 balls is even.)