(question is on the top) I wanna say it's 13, however I keep getting 18 as the answer, I've been stuck on this for awhile now. any help?

Mahnoor randomly selects times to walk into a local restaurant and observe the type of music being played she found that the restaurant was playing country 11 times rock & roll 17 times and blues 8 times use the observed frequencies to create a probability model for the type of music the restaurant is playing the next time mahnoor walks in.