A city council consists of 7 males and 4 females. Two councilors are selected at random to represent the city at an Elton John concert. What is the

A city council consists of 7 males and 4 females. Two councilors are selected at random to represent the city at an Elton John concert. What is the probability that,

a. both councilors are male?

b. one councilor is a male and one a female?

c. at least one councilor is a female?

Note: Express probabilities to 4 decimal places of accuracy. Hint: Construct a tree diagram.