Answer:
Probability is 
Step-by-step explanation:
This problem can be easily done tree diagram.
Few things keep in mind :
- From starting of match three victories of A.
- Less then or equal to two victories of B.
- In each matches there are two possibilities either favourable for A or B.
First case if A wins first match
- two victories of B then two of A
- victory of B then A then B then A
- victory of B then A then A
Second case if B wins first match(favorable)
- victory of two B then three A
So total cases are 4 and favorable is one
probability=
[Tree diagram is in attachment]
Remember the exponential law that says

therefor

the answer is C
Answer:
The total number of ways A, B, C, D, and E can sit together is 5
Step-by-step explanation: