Question

In bag A, there are 3 red balls and 7 blue balls, while in bag B, there are 6 red balls and 4 blue balls. These balls are identical except the color. From bag A, pick a ball randomly and then put it into bag B. (can not see the color of the ball picked from bag A). Now, from bag B, pick a ball. What is the probability to get a red ball? 0.57 0.55 0.70 0.64

Answer 1

Explanation:

The probability that you have picked a red ball is 3/10. You put that in bag B

Now the number of red balls is 7 and you have 7/11 of a chance of picking a red ball.

Suppose on the other hand, you pick a blue ball from bag A. That happens with a probability of 7/10. You put that in the blue bag. There are 6 red balls and 5 blue balls. The chances of you picking a red ball are 6/11.

So your total is 3/10*7/11 + 7/10 * 6/11 = .57