Question

the probability of taking 2 red marbles and 1 white out of a bag with 8 red, 3 white and 9 blue?

Answer 1

What you need to do is add all of the marbles together, no matter the color. So what is 8+3+9?

Answer 2

total of 20

Answer 3

And what is 2+1?

Answer 4

3

Answer 5

So do you know what your answer is? \[\frac{(total~marbles~drawn~out~of~bag)}{(total~marbles~in~the~bag)}\]

Answer 6

wait, its not that simple

Answer 7

Why do you say that?

Answer 8

3/20?

Answer 9

That would be correct....

Answer 10

Lucaz is right. It isn't that simple.

Answer 11

no way

Answer 12

No.

Answer 13

That's the way I learned it unless there is another part to it. I'm sorry...

Answer 14

@luffingsails go ahead and walk @lucaz through it then.

Answer 15

Hi, lucaz. Are you drawing with or without replacement?

Answer 16

no replacemnet

Answer 17

So, what you want is:

P(red) and P(red) and P(white).

Answer 18

well, the order doesnt mater

Answer 19

Right, order doesn't matter for this case.

Answer 20

any hint?

Answer 21

So, I can draw

red, red, white
red, white, red
white, red, red

So, 3 different ways, right?

P(A) and P(B) = ?

Do, you know?

Answer 22

P(A) you mean 2 red and P(B) 1 white?

Answer 23

P(A) and P(B) = P(A) * P(B)

So, we calculate each of the probabilities I listed and then we sum them together.