Kyle, David, and Catherine each try independently to solve a problem. If their individual probabilities for success are 1/3, 2/7 and 5/9, respectively, what is the probability that Kyle and Catherine, but not David will solve the problem? Choices
A) 35 / 189  B) 33 / 129  C) 25 / 189  D) 24 / 113  E) 20 / 189

Rationale: p ( kyle will solve ) = 1 / 3 p ( david will not solve ) = 1 - 2 / 7 = 5 / 7 p ( catherine will solve ) = 5 / 9 p = ( 1 / 3 ) * ( 5 / 7 ) * ( 5 / 9 ) = 25 / 189 answer : c
Answer: C