1. The question asks for the value of P(~A and ~B) - What equation to use?
The Attempt at a Solution
1. I am confused though, is P(~A and ~B) same as 1 - P(A and B)
or should I use, Pnot(A or B), and this is equivalent to 1 - P (A or B) ?
There is also another concept that I didn't fully grasp.
Lets say there is a lot of 20 pens.
and 60% that the lot has no defective pen.
30% contains 1 defective pen, and only 10% chance that the lot will have 2 defective pens.
So if a person selected 2 pens at random, and noticed they were NOT defective,
how does that change the probability of the rest of 18 pens still in the lot?? is it still 0.6 / 0.3 / 0.1 ?
Appreciate any help in advance.