Q:

A jar contains 10 blue marbles, 6 red marbles, and 3 yellow marbles. Cindy picks two marbles at random, without replacement.Which product gives the probability that both of Cindy's choices be red marbles?A) 6/19 × 5/19B) 6/19 × 6/19C) 6/19 × 5/18D) 6/19 × 6/18

Accepted Solution

A:
Answer: Choice C) 6/19 x 5/18========================================================Explanation:There are 6 red marbles out of 10+6+3 = 19 total. So 6/19 is the probability of picking one red marble. If that marble is not replaced, then we have 6-1 = 5 red marbles left out of 19-1 = 18 total. The probability of picking another red is 5/18We have 6/19 as the probability of picking red the first time, then 5/18 as the probability of picking another red marble. The first marble is not put back, and that marble is not replaced. --------------------------In terms of math notation, we can sayA = event of picking red on the first selectionB = event of picking red on the second selectionP(A) = 6/19P(B|A) = 5/18P(A and B) = P(A)*P(B|A)P(A and B) = 6/19 * 5/18