1, all three questions are correct: 80% * 65% *15%; 7.8%

2, the first question and the second question, the third question will not, but guessed the third question: 80% * 65% * (1-30%) * 25%; 9. 1%

3. The first question and the third question, the second question won't, but I guessed the second question: (1-60%) * 25% * 80% *15%; 1.2%

4, the second and third questions, the first question will not, but guessed the first question: (1-80%) * 25% * 60% * 30%; 0.9%

5, meet for the first time, the second and third time, but guess the second and third time:

80%*( 1-65%)*25%*( 1- 15%)*25%; 1.4875%

6, meet for the second time, not for the first time and the third time, but guess the first time and the third time:

60%*( 1-30%)*25%*( 1-80%)*25%; 0.525%

7, meet for the third time, not for the first time and the second time, but guess the first time and the second time:

20%*( 1-80%)*25%*( 1-60%)*25%; 0. 1%

8. None, but all the guesses are correct: (1-80%) * 25% * (1-60%) * 25% * (1-20%) * 25%; 0. 1%

The probability of all pairs is: 2 1. 1 125%.