Question

what is the probability of drawing a blue card, not replacing it, and then drawing another blue card?
(two red cards and three blue)

Answer 1

So you have 2 red and 3 blue cards, you draw 2 without replacement, right?

And you want the probably of both cards being blue.

Answer 2

yes

Answer 3

So, since these are dependent events (the outcome of drawing the first card changes the probability of the 2nd card being blue), you need to use:

P(blue, blue) = P(1st card blue)*P(2nd blue|1st blue)

Answer 4

So when you draw the first card, what is the probability that IT is blue?

Answer 5

3/5

Answer 6

You have 5 cards total, and 3 are blue. So what's the probability that you draw a blue card?

Answer 7

Right! now, when you draw the 2nd card, what is the probabilitiy that IT is blue, GIVEN THAT the 1st card was blue?

Answer 8

1/2?

Answer 9

Right! Because there are 4 cards left, and 2 of them are blue.

So now you need:
P(blue, blue) = P(1st card blue)*P(2nd blue|1st blue)

You have:
P(1st card blue) = 3/5
P(2nd blue|1st blue) = 1/2

So what is P(blue, blue)?

Answer 10

idk

Answer 11

OK, what do you not understand? Did you read what I wrote above?

Ask a question about whatever part you don't understand. That is how you will learn.

Answer 12

do you know the probability formula for dependent events?

When A and B are dependent, then:

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

Answer 13

ok

Answer 14

is the answer 3/10?

Answer 15

Yes.

Answer 16

thanks :)

Answer 17

sure :)