Dependent & Independent Events

[mwitte]

A bottle contains 25 marbles: 15 white, 5 green, and 5 blue. What is the probability for picking a white and then a green marble without replacing the first? To start I would put 15 over 25 and reduce that to 3/5. I would multiply 3/5 by either 5/24 or 4/24, but I'm not sure.

 

[Deleted member 4993]

A bottle contains 25 marbles: 15 white, 5 green, and 5 blue. What is the probability for picking a white and then a green marble without replacing the first? To start I would put 15 over 25 and reduce that to 3/5. I would multiply 3/5 by either 5/24 or 4/24, but I'm not sure.

After you have picked 1 white from a total of 25 balls:

How many balls are left for the next pick?

of those, how many are green?

So probability of picking a green ball, after you have picked a white ball - is .......................

 

[pka]

A bottle contains 25 marbles: 15 white, 5 green, and 5 blue. What is the probability for picking a white and then a green marble without replacing the first? To start I would put 15 over 25 and reduce that to 3/5. I would multiply 3/5 by either 5/24 or 4/24, but I'm not sure.

Without replacing makes the events dependent; replacing gives us independence.
In this case we multiply.

 

[Harry_the_cat]

Without replacing makes the events dependent; replacing gives us independence.
In this case we multiply.

In either case, we multiply. But what we multiply by changes.