Hi, my name is Andria. I have solved a question in data management. I thought I was on the right track, based on my lesson book. But my work and answer is different than those of others...and I don't understand what other people are doing when I read their threads. Pls help:

From a box of 12 flares, four are selected at random.

a) If the box contains four flares that do not work, the probability that all four will not work is 20.2%:

a= 4x= 4N= 12n= 4

p(x) = (C(a,x))(C(N-a,n-x)) / C(N,n)

= (C(4,4))(C(12-4,4-4)) / C(12,4)

= (C(4,4))(C(8,0)) / C(12,4)

= 0.002020 or 0.2%