Hey spark062.

For number 2, it's best if you draw a tree diagram.

You will have four leaves corresponding to no matches, 1 match, and 2 matches.

For the branch with two matches we have the first question with a probability of 3/10 since we start off with 10 questions of which 3 of them are ones we know. The second one however has only 9 choices (since we picked 1) with 2 of them being ones we can solve.

Both choices are independent which means we can apply P(A and B) = P(A)P(B) with P(A) = 3/10 and P(B) = 2/9. P(A and B) = 3/10*2/9 = 6/90 or given by R,

> 6/90

[1] 0.06666667

How did you come to the answer that you got? (Also can you show us your working for Q1 to get specific answers on those)?