Question

Suppose you choose a marble from a bag containing 2 red marbles, 5 white marbles, and 3 blue marbles. You return the first marble to the bag and then choose again. Find P(red then blue)

Answer 1

Red: 2
White: 5
Blue: 3
Total marbles: 10

P(R,B): (2/10)*(3/10) = 6/100 (with replacement)
Putting the marble back in the bag

if without replacement, not putting back in then:
P(R,B): (2/10)*(3/9) = 6/90