A bag contains 3 black, 4 red, 3 yellow, and 2 green marbles. What is the probability of drawing a b

Discussion in 'Calculator Requests' started by math_celebrity, Oct 27, 2021.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    A bag contains 3 black, 4 red, 3 yellow, and 2 green marbles. What is the probability of drawing a black and then a red marble out of the bag without replacing the black marble before drawing the red marble?

    The phrase without replacement is a huge clue on this problem.

    Take each draw and calculate the probability.

    Draw 1: P(Drawing a red)
    P(Drawing a red) = Total Red marbles n the jar / Total marbles in the jar
    P(Drawing a red) = 4/12

    4/12 simplifies to 1/3 using a common factor of 4:
    P(Drawing a red) = 1/3

    Draw 2: P(Drawing a black)
    P(Drawing a black) = Total Black marbles in the jar / Total marbles in the jar
    We drew one red marble already. Without replacement means we do not put it back. Therefore, we have 12 - 1 = 11 marbles left in the jar.
    P(Drawing a black) = 3/11

    The question asks, what is the the following probability:
    P(Drawing a Red, Drawing a Black)

    Because each draw is independent, we multiply each draw probability together:
    P(Drawing a Red, Black) = P(Drawing a Red) * P(Drawing a Black)
    P(Drawing a Red, Black) = 1/3 * 3/11
    P(Drawing a Red, Black) = 1/11
     

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