風之男

Hints:

(a) Let's rephrase the question a bit. Let's say we have 7 sports channels, 4 generic movie channels and "Movie 1" (for a total of 12 channels). We still pick 4 channels from the 12. What is the probability that "Movie 1" is selected?

(b) Presumably you have learned combinatorics (nPr and nCr), use it to tackle it. Remember probability is just "Number of Preferred Cases/Total Number of Cases", if you're lost with the multiplying/adding probabilities line of thought.

(b) is a very standard question. Try to understand it fully. Ask further if you're still stuck.