Let's denote the probability of selection of X as P(X). The probability of both brothers being selected, P(X and Y), is given as 0.09523809523809523. The probability of Y being selected is given as P(Y) = 2/7.

According to the multiplication rule of probability, the probability of both events X and Y happening together (both brothers being selected) is the product of their individual probabilities, assuming the events are independent:

P(X and Y) = P(X) * P(Y)

We can plug in the values we know:

0.09523809523809523 = P(X) * (2/7)

Now, we can solve for P(X):

P(X) = 0.09523809523809523 / (2/7)

P(X) = 0.09523809523809523 * (7/2)

P(X) = 0.09523809523809523 * 3.5

P(X) = 0.3333333333333333

So, the probability of selection of X is 1/3 or approximately 0.3333333333333333.
X의 선택 확률을 P(X)로 표시하겠습니다. 두 형제가 모두 선택될 확률인 P(X와 Y)는 0.095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238095238