- #1

kenny1999

- 235

- 4

## Homework Statement

Hello, i encounter a conceptual probability problem that I think i have come into confusio.

The situation is -

There are 3 Blue ball and 1 Red ball in a bag (BBBR), while there are 4 Green balls

in another bag (GGGG) If one of the balls is taken from bag A to bag B (not knowing which colours), then we draw two balls out of bag B (without replacement)...

what is the probability of drawing two balls of same colour? Another question is - what is the probability of drawing two balls of different colour

## Homework Equations

## The Attempt at a Solution

At first, because I don't know which ball was transferred from bag A to bag B, then I suppose there are four possible situation in bag B. That's GGGGB, GGGGB, GGGGB, GGGGR

under each possible situation, I set up a formula, (3/4)(2/3), then multiply it by 4.

But, the possibility is larger than 1, which means it's wrong. But I simply don't understand why.

How about if, I change the question a little bit. There are one more ball in the first bag, which is Green in colour which becomes BBBRG..

then take one of the ball from these bags (not specific) to the bag with 4 green balls

I think it's a hard conceptual problem to solve