## anonymous one year ago A bag has 1 red marble, 4 blue marbles, and 3 green marbles. Peter draws a marble randomly from the bag, replaces it, and then draws another marble randomly. What is the probability of drawing 2 blue marbles in a row? Explain your answer.

1. anonymous

@Nnesha

2. Nnesha

oky so i guess $\rm \frac{ blue~marbles }{ total ~number~of marbles }$

3. Nnesha

ahhh i'm not good 't probability stuff ?/>

4. Nnesha

@jim_thompson5910

5. anonymous

ITS OK THANKS

6. jim_thompson5910

@Nnesha you're on the right track

7. anonymous

Would it be 2/8

8. jim_thompson5910

you need to figure out how many blue marbles there are, out of how many total probability of picking blue = (# of blue)/(# total) since replacements are made, this means that the probability does not change on the second draw

9. jim_thompson5910

probability of picking 2 blue = (probability of picking 1 blue)*(probability of picking 1 blue)

10. anonymous

so im kinda lost...so it would be 2= 1x1?

11. jim_thompson5910

we have 4 blue out of 8 total so you agree that the probability of picking one blue is 4/8 = 1/2 right?

12. anonymous

yes

13. jim_thompson5910

the probability of picking 2 blue is equal to P(2 blue) = P(1 blue AND 1 blue) P(2 blue) = P(1 blue)*P(1 blue) P(2 blue) = (1/2)*(1/2) P(2 blue) = (1*1)/(2*2) P(2 blue) = 1/4

14. jim_thompson5910

this rule only works because replacements are made and each drawing is independent

15. anonymous

OK so what should i write down? @jim_thompson5910

16. jim_thompson5910

Basically those steps and the answer. But in your own words and format that's unique to you. Hopefully you see how I got that answer?

17. anonymous

yes thank u!

18. jim_thompson5910

you're welcome

19. Nnesha

thanks @jim_thompson5910 o^_^o