Question of the Day
There are 18 topics in a full-unit course, and the professor will ask 10 questions in the exam. (We assume each question is about one topic and only one question can be asked on each topic.) I'm supposed to answer 3 of these questions.
How many topics should I study for to make sure that I have studied for at least 3 of the topics that appear on the exam?
I know it is solved by combinations, but I don't know how! Help me out!
See the comments for the answer :)