Try drawing a tree diagram
for a the prob would aways be choosing 10 marbles.
for b the first marble would be choosing out of 10 the second choosing out of 9(since you are not replacing)
hope this helps
questions:
a) We have 10 marbles in a bag: 7 red, 2 blue, 1 yellow. We randomly pull two marbles, with replacement. Find the expected value of the number of blue marbles pulled.
b) We have 10 marbles in a bag: 7 red, 2 blue, 1 yellow. We randomly pull two marbles, without replacement. Find the expected value of the number of blue marbles pulled.
-I can't figure this one out without being given an actual value on the blue marbles, any suggestions?