SOLUTION: A jar contains two red and five yellow marbles. A marble is drawn at random and then without replacement, A second draw is made at random. Find the probability that the second marb

Algebra ->  Probability-and-statistics -> SOLUTION: A jar contains two red and five yellow marbles. A marble is drawn at random and then without replacement, A second draw is made at random. Find the probability that the second marb      Log On


   

Question 305941: A jar contains two red and five yellow marbles. A marble is drawn at random and then without replacement, A second draw is made at random. Find the probability that the second marble is red given that the first is yellow.
I have 2 out of 7 to represent the # of red marbles. And because there is no replacement, the second would be 5 out of 6. Using the Fundamental Counting Principal, I multiplied the two probabilities and got 10 out of 42.
My teacher says the answer is 14 out of 42, though. I have to prove whether that statement is right or wrong. Did I do something wrong? Please explain.
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
5/7 * 2/6 = 10/42 Probability of drawing a yellow and then a red one w/o replacement.
.
Find the probability that the second marble is red given that the first is yellow.
The answer to this question is 2/6
.
In neither case is 14/42 correct.
.
Ed