Its: ession (G. P.). If the sum of the first two terms of the A. P. is 6, find

12. (a) An association is made up of 6 farmers and 8 traders. If an executive body of 4 members is
to be formed, find the probability that it will consist of at least two farmers.
(b) The probability of an accident occurring in a given month in factories X, Y and Z are
1
I and I respectively. Find the probability that the accident will occur in:
5 12 6
none of the factories:
(ii) all the factories;
(iii) at least one factory.