(Probability that the problem can't be solve by A) P(B)=
2
3
(Probability that the problem can't be solve by B) and P(C)=
3
4
(Probability that the problem can't be solve by C ) Now the probability that the problem is solved by any one student of A,B and C=1 - the probability that the problem is solved by none of the students of A,B and C P(A∪B∪C)=1−P(A)P(B)P(C) =1−