Probability

[whitegrad02]

22. A bag contains 2 red balls, 3 blue balls, and 1 yellow ball.

c. How many blue balls must be added to the bag so that the probablitly of drawing a red ball is (1/5).

Any help as far as getting started or completing it would be nice. Thanks.

 

[stapel]

22. A bag contains 2 red balls, 3 blue balls, and 1 yellow ball.

c. How many blue balls must be added to the bag so that the probablitly of drawing a red ball is (1/5).

There are currently 2 + 3 + 1 = 6 balls. There are 2 red balls, so 1/3 are red, and the probability of drawing a red is 1/3.

For the probability of drawing one of the two red balls to be 1/5, the two reds would have to be 1/5 of the total number. Of what number is "2" one-fifth? So how many non-red balls (in this case, blue, specifically) do you need to add?

:wink: