List the cases in a systematic way:
4 alike
GGGG
WWWW
BBBB
3 alike, 1 different
GGGW
GGGB
WWWB
WWWG
2 alike, 2 alike
GGWW
GGBB
WWBB
2 alike, 2 different
GGWB
WWGB
BBGW
I think I got them all, check them then count them up
A sample of 4 balls is to be selected at random from an urn containing 18 balls numbered 1 to 18. Five balls are green, 6 balls are white, and 7 balls are black.
(a) How many different samples can be selected?
(b) How many samples can be selected that contain at least 1 white ball?
1 answer
1 answer