The probability that a person will get an electric contract is 2/5 and the contract that he will not get plumbing  contract is 4/7.If the probability of getting at least one contract is 2/3,what is the probability that he will get both?

A)  17/105     B) 17/106      C) 15/106     D) 18/106

Consider the following events: A=person gets an electric contract=person gets plumbing contract

We have,

P(A)=2/5,P(B)=4/7 and P(AUB)=2/3

Now (AUB)=P(A)+P(B)-P(A∩B)

=>2/3=2/5+(1-4/7)-P(A∩B)

=>P(A∩B)=2/3+3/7-2/3=17/105