Unfortunately, the number of students enrolled is not known. This must be known to calculate a numerical probability.
Suppose that there are 1000 students at the university. Then the probability that a given student picked at random is taking an art course is 17/1000, or 0.017.
Hopefully you have a calculator capable of calculating binomial probability (which is what is involved here).
The following function should give you your answer:
binompdf(1000, 0.017, 13) = 0.0657, or roughly 7%. The probability that 13 out of 1000 students will be taking an arts course during a given year is roughly 7%.