Answer:
8.33
Step-by-step explanation:
Conditional probablility P(A/B) = P(A and B) / P(B). Here, A is sum of two dice being greater than or equal to 9 and B is at least one of the dice showing 6. Number of ways two dice faces can sum up to 9 = (3, 6), (4, 5), (4, 6), (5, 4), (5, 5), (5, 6), (6, 3), (6, 4), (6, 5), (6, 6) = 10 ways. Number of ways that at least one of the dice must show 6 = (1, 6), (2, 6), (3, 6), (4, 6), (5, 6), (6, 6), (6, 5), (6, 4), (6, 3), (6, 2), (6, 1) = 11 ways. Number of ways of rolling a number greater than or equal to 9 and at least one of the dice showing 6 = (3, 6), (4, 6), (5, 6), (6, 3), (6, 4), (6, 5), (6, 6) = 7 ways. Probability of rolling a number greater than or equal to 9 given that at least one of the dice must show a 6 = 7 / 11
Answer:
2
Step-by-step explanation:
It sounds like we are pretending A is the universe. The only numbers in our world are 1,2,3,4, and 5.
You are given B is all numbers greater than 2.
The complement of B would all the elements not listed in B.
The elements in B are 3,4, and 5, since we are looking for numbers greater than 2 in our world of numbers above.
The elements not in B are 1 and 2.
So B complement is {1,2}.
There are 2 elements in our set for B complement. The elements that were counted were just the element 1 and the element 2.
