Probability: tree diagram

A bag contains six white marbles, and four blue marbles. Three marbles are drawn in succession. At each draw, if the marble is white, it is replaced, and if its blue it is not replaced.

.

a) draw a tree diagram with this information with all probabiltiies shown (2)

b) find the probability of drawing:

1) no mblue marbles (1)

ii) two blue marbles (1)

another question:

a comittee of 4 people is to be chosen at random from among 10 people.

what is the probability that both James and Sarah will be chosen.