Question 11

Explanation

The probability of selecting a student who wears a watch is determined by the ratio of students wearing watches to the total number of students. Let's calculate these components first.

Male students wearing watches:

Female students wearing watches:

Thus, the total number of students wearing watches ($n(A)$) and the total number of students ($n(S)$) are:

The probability of selecting a student who wears a watch is:

Therefore, the probability is $\frac{1}{2}$.