Urgent help statisics

(a) work out the probability of getting a partner from each of the firms individually, that is the number of partners in a firm out of the total staff for that firm (i.e for firm A this would be 3/5). Using the AND rule (you want a partner from firm A AND a partner from firm B AND a partner from firm C), you multiply each of these probabilities together to get the overall probability.

(b) this is the same as saying: the probability of not getting (only) 1 associate OR no associates. Therefore, because all possibilities should add up to 1, you can do 1, take away the probability from part (a) (that all three are partners), take away the probability that an associate is picked from A AND a partner from B AND a partner from C 'OR' a partner from A AND an associate from B AND a partner from C 'OR' a partner from A AND a partner from B AND an associate from C.

Remember that the AND rule means multiply the probabilities and the OR rule means add probabilities.