66. In the workshop, seven men and three women work. By their employee numbers, three people are randomly selected. Find the probability that all the selected individuals will be men.
Solution. Let's introduce the designations of events: $A$ - the first selected is a man; $B$ - the second selected is a man; $C$ - the third selected is a man. The probability that the first selected is a man, $P(A)=7 / 10$.

The probability that the second selected is a man, given that the first selected was a man, i.e., the conditional probability of event $B$ is: $P_{A}(B)=6 / 9=2 / 3$.

The probability that the third selected is a man, given that two men have already been selected, i.e., the conditional probability of event $C$ is: $P_{A B}(C)=5 / 8$.

The desired probability that all three selected individuals will be men,

$$
P(A B C)=P(A) \cdot P_{A}(B) \cdot P_{A B}(C)=7 / 10 \cdot 2 / 3 \cdot 5 / 8=7 / 24
$$