posted by JHONY .
The list of 16 topics was given to students to prepare for
exam. 16 students prepared themselves for all 16 topics, 6 students prepared
for 10 topics, and 3 students prepared only for 6 topics each. The rst
invited student was prepared for 2 topics contained in the ticket. What was
a probability that it was one of the students prepared for all 16 topics?