|
let's just utilize percentages here and say the sample size is 100. so essentially, there are 15 who are Rh negative and 85 who are Rh positive.
you could then think of the problem as arranging them in a line with the probability of the first 9 (since greater than 8) is Rh positive.
so then there are 100! ways of arranging this sample in a line. so then you could also think of it as the possibility of selecting an Rh positive person for the first slot in line as being 85, then for the second slot, there would be 84 possible ways of selecting that, then 83, then 82...77.
so now you have:
(85 * 84 * 83 * 82 * 81 * 80 * 79 * 78 * 77) / 100!
but there are also 85 choose 9 ways of arranging those nine selected slots. so i think, and correct me if i'm wrong, it's something like:
[ (85 * 84 * 83 * 82 * 81 * 80 * 79 * 78 * 77) / 100! ] * ( 85 choose 9 )
DAMN! just had dinner, and dimbulb beat me to it. don't know if my reasoning is right, but his sounds good.
__________________
no man or woman is worth your tears - and the one who is, won't make you cry
question authority, don't ask why, just do it!
|