A bag contains 10 white, 12 blue, 13 red, 7 yellow, and 8 green wooden balls.?

Question

A ball is selected from the bag, its color noted, then replaced. You then draw a 2nd ball, note its color and then replace the ball. What is the probability of selecting 2 red balls?

Answer 1

0.0676

Answer 2

With probability questions, you need to answer two questions:

1) How many possible outcomes are there? (this will be your denominator)

2) How many of those possible outcomes do I want? (this will be your numerator)

Because you replace the ball after each draw, you have two independent events. (This means the first event has no effect on the second one.)

So for the first draw, you have 50 balls to draw from (total possible) and 13 red ones (the number you want). For the first draw, then, the probability of getting a red ball is 13/50.

For the second draw, you still have 50 balls to draw from and 13 red ones, so the probability of getting a red ball on the second draw is 13/50, too.

The probability of getting a red ball on both draws is the probability for the first TIMES the probability of the second: (13/50)(13/50), which gives you .0676, or a 6.8% chance of this happening.

(Note this is different from the answer above. Multiplying 2 * 13/50 would give you the probability that you pull a red ball on the first try OR the second try, not the first try AND the second try.)

Answer 3

To easy.
Though the previous answer was on the right track...it is not complete. Indeed selecting 1 red ball is 13/50. the next time the chance is as big 13/50. That is 2 times 13/50 must occur. 2 * 13/50 = ????

Answer 4

well there are 50 balls, 13 read so the change of doing it once is 13/50...