Probability -- Help?

Sampling one at a time with replacement from a bag with 8 blue, 7 red, and 5 green. What is the probability of getting at least two red in 3 draws? The book says the probability is 0.2818 but doesn't explain why. Any help????

Unfortunately, the probability of picking 3 red balls in a row is not obtained by just cubing the probability of the first draw.

After the first draw (7/30), the probability for the second draw changes to 6/29 and the third to 5/28. This is because the drawn balls are no longer in the pool of those to be drawn. However, if you are replacing the balls after they are drawn, this does not apply.

These changes need to be applied to the other problems.

I hope this helps a little more. Thanks for asking.

probability of drawing a red ball is 7/20. You have to add up the probability of 2 and 3 red balls out of 3 draws.

Probability of 3 red out of 3 is

(7/20)^3

Probability of 2 red out of 3 is

(7/20)^2*(13/20)*3

13/20 is the probability of drawing a ball of different color and the factor 3 is the number ways that lead to this outcome, i.e. you can draw the other ball the first time, the second time or the third time.

(7/20)^3 + (7/20)^2*(13/20)*3 = 0.28175



This problem is small enough to draw a probability tree. The probability of picking red on any draw is 7/20 = .35. Ergo, the probability of NOT picking red is 13/20 = .65.

So, the probability of picking red in all draws is .35*.35*.35
There are three ways to pick red 2 out of three times (d1,d2) (d1,d3), and (d2,d3). Each of these, separately, has a probability of .35*.35*.65

Take it from here.

hey i need help with theas 2 problems

prob.1[Ms. Madison sends 3 out of every 5 quilts she makes to a shop in Georgia.How many quilts are sent to the shop if she makes 20 quilts?

3/20 or 15%

  1. 👍 0
  2. 👎 0
  3. 👁 108
asked by Cheri
  1. If there are 10 red marbles and 30 blue, what is the probability of randomly selecting a blue marble?

    use the following format: 0.XX

    e.g. if there are five red apples and five green apples the probability of randomly selecting a green apple is 0.50

    1. 👍 0
    2. 👎 0
    posted by igyy

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    I need some help with the set up please. Joella has a bag of marbles. The bag contains 10 red marbles, 5 green marbles, and 3 blue marbles. She will randomly select 2 marbles from the bag one at a time without replacement. What is

    asked by Dallas on March 4, 2018
  2. math-algebra

    7. A bag contains 5 red marbles, 6 green marbles, and 9 blue marbles. Suppose 3 marbles are chosen without replacement. What is the probability of choosing a red, a blue, and a red in that order?: A. 9/320 B. 5/152 C. 1/1280 D.

    asked by Anonymous on September 26, 2007
  3. probability

    A bag contains 8 red, 12 white and 4 blue marbles. If 2 marbles are selected in succession (without replacement), find the probability as a common fraction in simplest form that first is red and second is blue

    asked by james on August 17, 2014
  4. math-algebra

    7. A bag contains 5 red marbles, 6 green marbles, and 9 blue marbles. Suppose 3 marbles are chosen without replacement. What is the probability of choosing a red, a blue, and a red in that order?: A. 9/320 B. 5/152 C. 1/1280 D.

    asked by Anonymous on September 26, 2007
  5. Statistics

    a) What is sampling with replacement? (b) What is sampling without replacement? c) How does sampling without replacement affect the probability of events, compared to sampling with replacement?

    asked by Anonymous on February 16, 2014
  6. probability

    George has a bag of marbles. Inside the bag are 5 red marbles, 3 red marbles, and 2 blue marbles. He draws out two marbles in a row, without replacement. What is the number of outcomes?

    asked by Piggy on February 22, 2012
  7. probability

    You have a bag with 3 red, 3 white, and 2 blue balls in it. You draw three balls without replacement. What is the probability that the 3rd ball chosen is blue?

    asked by Anonymous on November 22, 2015
  8. Probability/Statistics

    1)Two marbles are chosen at random from a bag containing 3 blue and 2 red marbles. The relative-frequency histogram shows the distribution of the number of red marbles chosen. Find P(0 red). (the gragh shows 3/10 for 0 red, 3/5

    asked by Jon on February 7, 2008
  9. Stats

    A bag contains 13 marbles; 3 blue, 2 green and 8 red. Without replacement find the following probabilities. a) P(both have the same color) b) P(different colors) c) P(G2|R1) d) P(G2 or R2) e) P(no red marbles) f) P(G2 and B2)

    asked by Nichole on March 2, 2012
  10. Math Statistics

    A bag contains 13 marbles; 3 blue, 2 green and 8 red. Without replacement find the following probabilities. a) P(both have the same color) b) P(different colors) c) P(G2|R1) d) P(G2 or R2) e) P(no red marbles) f) P(G2 and B2)

    asked by Nichole on March 2, 2012

More Similar Questions