Question

A bag contains a 1 red counter, 2 blue counters and 1 white counter. You pick 1 counter at random. Then you pick a second counter without replacing the first counter. 1. Draw a tree diahram to show all possible counter combinations. 2. What is the probability of picking 1 red counter and 1 white counter (in either order)?

Answer 1

1/12 chance

You have 4 counters and want a red (1/4) then a white, but don't replace any which gives you (1/3) *since you don't replace the other one...* Then you multiply the two (1/4*1/3) and you should get 1/12.