The question is in the description

Question

A jar contains 5 blue marbles, 8 red marbles, 4 white marbles, and 3 purple marble suppose you pick one at random. Find the probability of drawing a red, then white marble, if the 1st one is but back.

Answer 1

First let's find the probability of drawing a red marble.  I know that the probability is my (# of red marbles)/(total # of marbles) so 8/20 which we can simplify to 2/5.

 

Since the first marble is put back, I know that I will still have 20 total marbles.  Therefore the probability of drawing a white marble is (# of white marbles)/20 which is 4/20.  We can simplify this to 1/5.

 

The probability of drawing a red marble and then a white marble is going to be the product of these probabilities.

 

Therefore the total probability is the probability of the first even occurring times the probability of the second event occurring.

 

(probability of red)*(probability of white) = total probability

(2/5)*(1/5)=2/25

 

So we can expect to draw a red marble then a white marble 2 out of 25 times that we perform this experiment.

 

Hope this helps!

Answer 2

Hello, thank you for taking the time to post your question!

There are a total of

5 + 8 + 4 + 3 = 20 marbles in the jar, 8 of which are red and 4 of which are white.

So that means we have a 8/20 chance of the first draw being red and then a 4/20 chance of the second draw being white since the first one is put back. To find the overall probability then you can just multiply those together

8/20 x 4/20 = 32 / 400 = 2/25 = 0.08

So there is a 2 in 25 chance of this situation occurring, is the idea there!

I hope that helps you get moving in a better direction on this type of question! Feel free to reach out if you have any additional questions beyond that :)