A check of dorm rooms on a large college campus revealed that 38% had refrigerators, 52% had tvs, and 21% had both a tv and a refrigerator. what's the probability that a randomly selected dorm room hasa.a tv but no refrigerator?b.a tv or a refrigerator, but not both?c.neither a tv nor a refrigerator?

A) 31%
B) 48%
C) 31%

Explanation
52% had TVs, including the 21% that had both.  52-21 = 31% of students that only had a TV.
38% had refrigerators, including the 21% that had both.  38-21=17% that had only a refrigerator; combining this with the 31% that had only a TV, 31+17 = 48%.
100-(17+21+31) = 100-69 = 31% had neither.