
Ian B. answered 08/20/20
PhD candidate in Mathematics
You're very close. Using the word combination here might not be the best idea. Why not (think about order)? How many answer _______ can be correct?
To verify your answer, you can try solving it a different way. What is the probability of correctly guessing the answer for a single question? Is guessing correctly on Problem 1 dependent on guessing correctly on any other problem? Is it the same for all 10 problems?