There are 5 red marbles, 15 blue marbles, and 5 green marbles in a bag. You reach in and randomly draw a marble, replace it, and draw another marble. What is the probability that the first will be red and the second will be blue?

Question

anonymous · Answer

since you're sampling with replacement the probabilities will be independent. as such the joint probability will just be the product of P(red)*P(blue)

anonymous · Answer

Okay thanks

anonymous · Answer

please note that perl's response has an error.  the denominators will not change

anonymous · Answer

see, so one's perfect

perl · Answer

5 / ( 5 + 15 + 5 ) * 15 / ( 5 + 15 + 5 )

anonymous · Answer

@perl, you may want to read the code of conduct (below, left)

perl · Answer

no thanks

anonymous · Answer

So would the answer be about 20%?

anonymous · Answer

what did you get for P(red)?

anonymous · Answer

I'm confused. Do you mean the number of red marbles or is there something that isn't very obvious and I should know? xD I'm pretty new to this sort of stuff ^^;

anonymous · Answer

Oh wait never mind, I figured it out. Thanks! =D