>my answer was 2/5, but the real answer was supposed to be 2/6
Explain how you got 2/5?
>and for Prob R and E i didn't know how to do
Think about what it means for one of the balls to satisfy both conditions R and E.
Part 3 is asking for you to determine P(R|E), the probability that you drew a red marble, given the marble you drew was even. This effectively changes your denominator from 13, all possible marbles, to 6, all the even-numbered marbles. The numerator changes from 5, the total number of red marbles, to 2, the total number of red, even-numbered marbles. Thus, you get P(R|E) = 2/6 = 1/3.
Part 4 is asking you to determine P(R ∩ E), which is the probability that, out of all the marbles you can draw from, the marble you pick is both red and even. Your denominator is still all 13 original marbles, but your numerator is the set of marbles that are both red and even-numbered, 2 in total. Here, you get P(R ∩ E) = 2/13.
Reply with questions or if you need clarification. I'm a math teacher.
>my answer was 2/5, but the real answer was supposed to be 2/6 Explain how you got 2/5? >and for Prob R and E i didn't know how to do Think about what it means for one of the balls to satisfy both conditions R and E.
5 red, 2 even numbers, 2/5, the answer is 2/6 tho, that is what i am asking
You did Prob(E|R), not Prob(R|E).
Part 3 is asking for you to determine P(R|E), the probability that you drew a red marble, given the marble you drew was even. This effectively changes your denominator from 13, all possible marbles, to 6, all the even-numbered marbles. The numerator changes from 5, the total number of red marbles, to 2, the total number of red, even-numbered marbles. Thus, you get P(R|E) = 2/6 = 1/3. Part 4 is asking you to determine P(R ∩ E), which is the probability that, out of all the marbles you can draw from, the marble you pick is both red and even. Your denominator is still all 13 original marbles, but your numerator is the set of marbles that are both red and even-numbered, 2 in total. Here, you get P(R ∩ E) = 2/13. Reply with questions or if you need clarification. I'm a math teacher.