Hello mneoxFirst an administrative note: in future, post each question as a separate thread. (See rule 14.)

If we choose a group of people, then to find the probabilities of each number from to watching AI we use the Binomial Distribution formula. This says that the probability that exactly of them watch AI is:where is the probability that any given person chosen at random watches AI.

So here, , and . So we need to find and and add them together. I'll start you off:Can you complete it? (I make the final answer .)

-----------------

You need to understand what intersection, , and union, , mean in set theory. So read what I'm saying here really carefully.got a question here too..

1) Why does P(A and Complement of B) = 4/18?

2) Why does P(A or Complement of B) = 13/18?

i got some questions about that because for #1, why do you not count the middle 3 dots that they share? Cause in #2 you count them for some reason. As for #2, why do you count the outside dots as well, and why do you count the middle 3 dots?

The set (A and complement of B) - which is denoted variously by or or - is theintersectionof the set with the set ; that is, the set of elements that are inbut notin .

So means the probability that a dot chosen at random is inside loop but not inside loop . There are four dots in this region, out of a total of dots. So the probability of this is .

The set (A or complement of B)- which is (or ... etc) - is theunionof set with set ; that is, the set of elements that are inor notin . The only elements that will be excluded from this set, then, are those that are in but not in . There are just of these in the diagram; the remaining are in . So the probability that a dot chosen at random is in this set is .

Grandad