Question

you roll 2 dice. what is the probability that at least one of them is a 6.

Answer 1

Let A denote the event that one specific die is a 6.

Let B denote the event that the other die is a 6.

P(A) = 1/6
P(B) = 1/6

Note that the events are independent.
.: P(A˄B)=P(A)P(B)

So we need to find: P(A˅B)

Use the exclusion principle:
P(A˅B) = P(A) + P(B) - P(A˄B)