## kcla1996 3 years ago Two urns each contain green balls and blue balls. Urn I contains 4 green balls and 6 blue balls, and Urn II contains 6 green balls and 2 blue balls. A ball is drawn at random from each urn. What is the probability that both balls are blue?

1. JakeV8

The probability of drawing a blue ball from each urn is the probability of drawing a blue ball from the Urn 1 multiplied by the probability of drawing a blue ball from Urn 2.

2. JakeV8

It is sort of like flipping 2 coins and asking for the chance of getting 2 heads. The chance of getting a head on Coin 1 is 1/2, and it's the same for Coin 2. The chance of getting heads on both coins is (1/2) * (1/2) = (1/4)

3. JakeV8

But in this problem the probability is different for drawing a blue ball because there are different numbers of blue and green balls.

4. kcla1996

A 2/51 B 3/20 C 1/10 D 4/153

5. kcla1996

i still do not understand

6. JakeV8

How many total balls in Urn 1? 6 blue + 4 green = 10 How many are blue? 6 blue So, the chance of drawing a blue ball out of Urn 1 is: (# of blue balls) / (total # of balls) = 6 / 10

7. JakeV8

Does that help? Now you can do the same thing for Urn 2... find # of blue balls / total balls in Urn 2

8. kcla1996

but the answer isn't up there ^

9. JakeV8

what did you get for Urn 2?

10. kcla1996

1/4

11. kcla1996

so do i multipy 6/10 and 1/4

12. JakeV8

Sounds right to me. So the probability of 2 blues is (6/10) * (1/4) = (6 / 40)

13. kcla1996

3/20

14. JakeV8

right :) I didn't see it at first, but once you simplify the fraction, it's there :)

15. kcla1996

thanks for the help

16. JakeV8