## briana.img one year ago Someone help me understand this problem?

1. briana.img

A bag has 4 green marbles, 3 red marbles, and 3 yellow marbles. What is the probability that you pick a green marble, do not replace it, and pick a red marble?

2. Owlcoffee

Well, I believe these are two scenarios. First calculate the probability you have to pick a green marble, you count all the marbles and and the green marbles: $\frac{ 4 }{ 10 }.100$

3. briana.img

why the 100?

4. Owlcoffee

it's there by mere definition, but it's a formula that gives you the probability.

5. Owlcoffee

You have to first perform the division, remember that.

6. briana.img

I got 40

7. Owlcoffee

Good, now, that gives the probability you would have to get a green marble, now, you won't put it back in the bag, so now you have a total of 9 marbles inside the bag. What would be the probability to find a red marble in the new quatity?: $\frac{ 3 }{ 9 }.100$

8. briana.img

got 33.33

9. perl

Better not multiply by a 100. Only if you want to convert the final answer to a percentage $$\Large \sf Probability = \frac {4}{10}\cdot \frac{3}{9}$$

10. briana.img

2/15??

11. perl

yes

12. briana.img

awwwh okay thank you! i'll look at this next time i have trouble with this

13. Owlcoffee

Haha, I was doing it by parts, but thanks, perl.

14. briana.img

@perl @Owlcoffee so for the problem A bag has 5 red marbles, 6 blue marbles and 4 black marbles. What is the probability of picking a blue marble, replacing it, and then picking another blue marble? the answer would be 4/25 ?