A group of 60 students were surveyed about the sports they play: football, basketball, and tennis. 12 students play all three sports. 35 students play football. 8 play football and basketball but not tennis. 18 students play basketball and tennis. 4 students do not play any of the three sports. All 30 students who play tennis play at least one other sport.
Two of the 60 students are chosen at random. Work out the probability that they both play basketball.
