Carcass wrote:
In a newspaper printing factory, 10 out of every 100 newspapers are found defective due to some defects in the printing. If two newspapers are randomly selected, what is the probability of getting exactly one defective newspaper?
A. 1/11
B. 2/11
C. 3/11
D. 4/11
E. 5/11
I have a simpler method that doesn't use combinatrics.
Let defective be d, and not defective be n. We basically want P(d and then n) + P(n and d).
P(d and then n) = P(n and then d) = .1 * .9.
To get what we want = 2 * .1 * 9 = 0.18. Only answer choice B = 0.18.