A box contains 6 white balls, 4 black balls, and 1 red ball. How many red balls must be added to the box so that the probability of drawing a red ball is 8/9? HOw many black balls must be added to the original box so that the probability of drawing a white ball is 1/9?

Question

cwrw238 · Answer

the total number of balls after adding more red balls must be a multiple of 9 ( for the probability to be 8/9)
then the probability of drawing a non red ball will be 1/9 - and there will be 10 of these.
so can you figure out how many reds to add now?

cwrw238 · Answer

what will be the total number of balls after the red balls have been added?

anonymous · Answer

I am so very confused with this question. I have always had a problem with these :) I am trying to figure this out with what u said.

cwrw238 · Answer

hint  - there are 10 white and black balls - and that is 1/9 of the total  (since probability of picking one  is 1/9)

zarkon · Answer

solve

$$\frac{1+x}{6+4+1+x}=\frac{8}{9}$$

for $x$